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Further Explained: Apple’s iMac 2011 Model Hard Drive ‘Restrictions’

It’s incredible the coverage generated by yesterday’s blog article on the further iMac upgrade restrictions. I’d like to personally address some questions, context, and provide additional technical detail concerning this issue.

I want to be very clear that I think these are absolutely the best iMacs ever. These machines up the game considerably and provide performance that can even match up with the Mac Pro for a lot of applications. We’ve been excitedly covering these new iMacs starting with an unboxing and teardown blog post just hours after they were first introduced.

Most iMac buyers (and buyers of anything Apple in general) are more than satisfied with how things are right out of the box. The vast majority will never even think about after purchase options that Apple does support, such as installing additional memory. These are great systems right from the get-go… But pardon us or anyone who wants to make them even better. :)

What is our testing environment/parameters?
In our lab, we have all the different flavors of iMac 21.5″ and 27″ 2011 models currently shipping. This includes one or more of each model processor option and/or video option. Apple’s current latest 2011 iMac models have Apple Model Identifiers of iMac12,1 for the 21.5″ and iMac12,2 for the 27″ regardless of what base model/options selected.

The OS installed is 100% up to date as of all updates available today including the recent EFI update which
enabled 6.0Gbp/s SATA 3.0 capability with two of the iMac’s three SATA ports.

From the iMacs, these model drives were found present in the systems we received:

  • Seagate ST3500418AS 500GB 7200RPM Barracuda 7200.12 7200RPM 16MB SATA 3Gbp/s
  • Seagate ST31000428AS 1TB 7200RPM Barracuda 7200.12 7200RPM 32MB SATA 3Gbp/s
  • Western Digital WD1001FALS 1TB Caviar Black 7200RPM 32MB Cache SATA 3Gbp/s

Note: You don’t get to pick what brand hard drive, cache, model, etc are installed at the factory. Apple iMac Specs do confirm all factory hard drives are 7200RPM. Of further note, the base $1199 iMac model doesn’t have any factory drive configuration options – it is only offered with the 500GB capacity drive.

The following non-Apple Drives are new units pulled from OWC’s drive inventory:

***and a ‘zinger/wildcard***
*Unaltered, current drive – but also used for other previous testing. Same Western Digital WD1001FALS 1.0TB Caviar Black 7200RPM 32MB Cache 3Gbp/s model as we found in one of our factory iMacs, but this one was pulled out of one of our 2010 Apple Mac Pros. This is an Apple Factory/Apple Rom unit from before these new iMacs rolled out of the same drive model p/n of one of the 1TB models we’ve so far seen used in the new iMac 2011.

Note: Systems were booted and then left with sleep off, display on. We did not put these iMacs under any kind of stress load that could otherwise impact the system temperature and result in fan speed changes. The ambient temperature of the room being tested in was between 72 and 76 F.

Our results:

Apple Rom/Factory Drives from received iMac 2011 models:
Regardless of what drive brand model was factory installed, any of the different drives we received in any of the iMacs worked fine in any other…

WD where Seagate 500 or 1TB was and vice-versa. Apple Rom/Factory drives worked interchangeably and no fan rev or Apple AHT failure. Even after a couple hours, the reported HDD Bay fan speed remained right about 1100 in both 27″ and 21.5″ 2011 Apple iMac models as reported by SMCFanControl.

Results from all other drives we tested in those iMac 3.5″ drive bays:
(including the same model Apple Factory Rom 1.0TB WD drive from our Mac Pro 2010)

Didn’t matter which drive, no drive, or which iMac. Consistently the same result in each and every one of our iMac model variants. AHT test = FAIL due to thermal sensor failure.

After startup, the HDD fan would start to ramp up from the 1100RPM base and into the 5600RPM range as reported by SMCFanControl. This didn’t happen instantly, but over the course of 30-40 minutes typically. Within just a couple minutes though, the fan speed would be up over 2500RPM and it’s a steady rise from there before the peak.

iMac 2011 fan 5600
Conclusions and further comments:

Apple AHT – why this not working can be a problem:
When you have a problem with your system, Apple Hardware Test is often suggested for determining if the problem is… well… with a hardware component. If you can not run this test, it could impact support or even warranty response for an iMac with an issue unrelated to the hard drive. Certainly in a production environment, you want to know your system is 100% go-go-go. Not being able to run Apple AHT can be a detriment in this way, although admittedly something that many can do just as well without.

Fan Speed:
Depending on your environment, this may not matter. While the fans are definitely noticeable in an quiet space, Apple does use fans that are very quiet even at higher speeds. The noise I observed is more from actual air movement through the channels vs. noise from the fans themselves.

In my opinion, the following should be an industry standard thing…. and maybe it will be. Currently, each Hard Drive manufacturer has different pins for the available thermal sensor line found on today’s hard drives. As an example of this: owners of 2010 iMacs can more easily replace their factory hard drive with a retail available drive, as long as they stick with the same make (it’s still a major job just to open up these machines, independent of other challenges). They could also use a different make, but they would need to make some modifications.

What I am trying to say is that Apple didn’t make any barrier with the 2010 (or 2009) models with that respect, the barrier to plug & play drive options in this case is a lack of industry drive standards on the extra drive pins. So, perhaps use of this additional line on the power connector (which is standard on all SATA drives) might be an industry standard in the future.

And if so – then it’s only Apple today, with a firmware set that enables this feature, which just isn’t standard on retail drives yet. If so – it might not be as big a deal. There is still a question I’d like to know the answer to – why isn’t Apple simply using the S.M.A.R.T. reporting feature of today’s drives for the drive temperature information? That doesn’t require/use any extra pin out/line out and I am not aware of any disadvantage from utilizing this option. Maybe someone out there has insight on Apple not using the thermal data via S.M.A.R.T.?

What’s different between the power connection/leads for the HD bay vs. the other bays:
First, note that the HD bay has a different power connection with seven total leads, two of which are used for thermal feedback. Normal SATA power connections, including those going to the SSD and optical bay in the 2011 iMacs, utilize five total leads.

Depending on the Apple factory drive brand, voltage on this line is held at a steady rate with a pulse about every two seconds during which the voltage falls within a consistent range before coming right back up. What’s interesting is that the voltage range, and this is contradictive to my suggestion this could be a future industry standard thing, is that the different brand drives have a different ‘hold voltage’ and ‘drop pulse’ range observed. Furthermore,when we connect up a drive that was not originally shipped in one of these iMac 2011 models, the pulse pattern is no longer present.

Although the differences between drive brands here raise questions about possibility of industry standardization, the fundamentals appear similar – just a different starting voltage possibly. Noting that external thermal sensors provide the thermal data by voltage passed – with resistance on the line affected by the temperature of the sensor that results in voltage read change, so still could be a standardized industry function future forward…. Either that, or Apple has trusted firmware/data it gets from the installed drive and unless it’s the Apple drive – it doesn’t recognize/do the thermal profiling via the power line…. Ok, that’s pretty confusing…. We have done other testing with external options, but it’s so far inconclusive – so can’t say anything is 100% definite yet other than: either Apple has custom firmware in its drives that enables something, or Apple has firmware on the drives that it looks for to use what is there anyway.

Possible Solutions:
*NOTE – NOT FULLY TESTED/Approved/Recommended, etc.* I strongly caution, we’re looking at a number of scenarios and doing a lot of testing to determine what is going to make sense and be reliable and implemented in a way that best maintains the Apple warranty on the system as well.

If we short those two lines vs. connect to the drive (factory or otherwise), the fans don’t rev and Apple AHT does pass. We have been aware of this and see upgraders in the field now reporting this as well. When you do this though, our best guess is that the thermal reporting in the iMac is being told that the bay is empty. When we see an Apple stock iMac with SSD only, we’ll be able to see if this is how Apple handles that bay being empty.

The problem with this solution is running a drive in the bay means that heat isn’t being measured. Of which, a consequence could ensue for obvious reasons.  The bottom line is that the iMac HDD bay can heat up and the iMac doesn’t know and doesn’t do anything about it.

HDD Fan Control appears to be another option and a solution to the above.

This utility uses the S.M.A.R.T. Data to monitor drive temperature and allows you to set the temperature parameters for what speed the HDD bay fan runs at. It will hold the fan speed at bay, based on temperature parameters you give it, and prevent the fans from revving up to unnecessary and noticeable levels…. Again, th0ugh, why doesn’t Apple use S.M.A.R.T. Data?

By itself, this software can solve the fan rev up issue. Combine that with the short solution above, and you appear to have an iMac with fans under control and that you can run Apple Hardware Test (AHT) with normal results.

One concern with using any utility to limit the fan speed is what if your settings are too low for heat? We don’t know Apple’s exact parameters or collected data points from the HDD bay for thermal, and there is a potential for issues should the bay be allowed to become too warm without the proper fan speed engaging.

The bottom line is that work around options are in play now, and with further testing, we should be able to be confident in one solution of another. Whatever the solution – the best solution, in my opinion, would be not needing to find a solution in the first place. Certainly it’s a very small percentage that are even going to want, or need, to replace drives in their iMac… Apple made that hard enough as it is… But for those few, it didn’t need to be this hard.

When we have more on this, we’ll share it right on the blog. And…

I absolutely welcome any feedback and details concerning work arounds you’ve implemented, especially if you have installed a non-Apple drive and had AHT pass. I’ve read various posts out and about, but most don’t have a lot of detail (and I suspect really didn’t check fan and/or AHT results and also seen an initial all good report and then a follow up post after noting the fan and AHT issue).


UPDATE 8-23-11:

We’ve developed a workable hardware solution to the fan sensor problems and are now offering it as part of our Turnkey Program for 2011 iMac.


OWC Larry
the authorOWC Larry
OWC Founder & CEO
Larry O'Connor is the founder and Chief Executive Officer of Illinois-based Other World Computing (OWC®). Starting as a one-man business in 1988, O'Connor has provided the leadership and vision to establish OWC as the leading provider of technology products and services today.
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  • Here we are 11 or 12 years down the road. I’m looking at an iMac a client just brought me and based on the AHT results I thought I had figured out it was a bad (Crucial) SSD install. She just inherited this iMac so we don’t know if, or how, it was working before. To keep a very very long story short, there were other problems to overcome first, involving the new owner’s attempts to upgrade the OS; I received it with a blank drive.

    I see elsewhere that this particular model of 12,2 was also prone to graphics card failures. What I’d like to know is: if the SSD upgrade will automatically throw an error, does AHT stop at that point, preventing testing of a possible graphics card problem?

    • This is a great question! The apple test will give you any errors that are present. However when it reaches an error it stops at that error. The SSD, if the SSD is fine and no OS is on the drive then it should not have an error. Any questions on the AHT I would suggest reaching out to Apple since this is their testing for the machines.

  • I am totally devastated. I have (HAD) a 2011 27inch IMac
    took to shop to have it cleaned out since it was running hot. then add SSD drive to it and
    couple extra rams. turned on at shop working. took home well padded back seat.
    Turned on at home absolutely nothing. took back next day. I was told it must be the power source. So I told them replace. They had trouble and several times could not get it back together kept shorting out. Now I am told not fixable. I am lost without my IMac.
    Is there anything that can be done with it.?????
    Now they tell me that the hard drive can only be read by another Mac. I had to go out buy HP Pc since My budget at 73 is very minimal.
    Is there any hope for me.? Is all my info lost? I was hoping to at least access from PC.

  • Can I install a WD Blue 4TB or 6TB HDD in a Mid 2011 27″ iMac as my storage drive???

    • Yes – you can use just about any SATA 3.5″” HDD in your iMac 2011 using our SMC thermal solution

      This communicates with Apple’s SMC system so it is getting bay temperature and further doesn’t just rev the fans to 100% from a non-Apple Rom drive causing a fault read. Goes in line with the drive to supply the correct data to Apple’s monitoring system which is part of Apple HD Firmware on factory rom drives.

      All that being said – I’d highly recommend a faster hard drive or even consider an SSD. If you don’t currently have an SSD installed, the same link at the top here also has kits for adding an SSD to the SSD bay all 2011 iMacs have. An SSD will make that system feel like it’s been replaced with what has to be brand new.

      Hope this helps.

      • Hi Larry,

        First I want to say thanks for the fast reply and the info. I already have a 1TB SSD for my OS and programs but your saying I should go with a faster HDD just for storage? 5400 rpm or 7200 rpm? I didn’t think I needed speed just for storage.

          • Ok perfect. So 4TB or 6TB would work fine with no problems correct? I read somewhere that the larger HDD couldn’t be formatted because it was to large. Have your head of anything like that before? But all i need to do is attach the heat sensor, which i already ordered today.

            Thanks for all your help.

  • Have IMac 2011 27 inch in shop right now….. they replaced hard drive and added 4 gigs of ram… what I could afford on SS.
    Worked fine until I got it home plugged in and would not turn on. Took back next day. Told power source went out. Replaced. Now new issue
    When they are trying to put screen back on it keeps shorting out..’What could be the problem?
    AT 73 I am not sure if I am ready to try fix myself.

  • Hello , I️ have a 2011 MacBook Pro 13 inch and I️ was just informed that my internal hard drive has crashed . I’m able to log in but it takes forever and a day . Is there anyway you guys can fix this .

  • HI, Thank you for your article. Are you saying that only the factory installed drives work and replacing the drive with even the exact brand/model of drive will result in thermal sensor failure ?

  • I bought and did the hard drive upgrade on my 2011 imac with an ssd behind the optical drive in 2014. The last few months though I have noticed excessive heat and fan usage(and noise).

    I installed a WB Black 3TB drive and 250GB Samsung EVO SSD. I created a Fusion Drive.

    I would like to correct the fan and heating issue. I’ve also had optical disc issues, so I can and would like to remove the optical disc. I’m guessing I can just unplug it. Will that help my heating issues? Would a different drive help. I’m ok with going down to a 2TB drive if that helps.

    Thank You.

  • Can I install a 3TB HDD into my late 2009 27″ iMac.
    Ive swapped the original WD 1TB for a WD 3TB but when I try to format using disk utility the error says The disk is too large to be supported by the given partition scheme.

    What can I do

  • My question is, can i put a Late 2013 27 inch iMac hard drive it came with, into a 2011 iMac? Which already has an OWC wire with a Samsung SSD and a 3rd party 3TB drive in it. (which I’m replacing with the 2013 drive.

    • Great question! The 3.5″ HDD from your 2013 will work with your 2011 iMac without any problems! You have the OWC In-Line Digital Thermal Sensor Cable but if you didn’t, you would need it!

      Let us know if you have any further questions.

  • Hi Larry – I have a Mid 2011 iMac which I bought second hand about 3 years ago. The fan noise issue arose quickly and I didn’t really pay attention at first, thinking it was a natural reaction to overheat situation. It was a “spare” Mac for me so not used frequently. Now I do use it more frequently and am getting more annoyed at the constant whirrr of the fan with really cool air coming out of the machine. The Mac does not feel overheated at all. Having read your very thorough article above, I can only now assume the previous owner had changed the drive. While I have been used to opening Macs and doing a lot of stuff (over 25 years user), opening the iMac and getting to components appears more of a “risk”. It’s such a sleek and beautiful machine, I would hate to hurt it accidentally. It’s been about 5 years since your article appeared – I wonder if anything new and easier was discovered to eliminate fan noise. I did try (the demo) HDD Fan control and that worked for an hour demo. But, as you say, this method might still prove a longer-term risk by damaging something else. And I find the US$ 40 price tag of HDD excessive.
    So- in summary, have any other “safer” fixes been identified. I can actually live with the fan noise which does stop after a while in sleep mode – but would welcome any more recent ideas/findings. Thanks for your help. Alain Saunders

      • Hello Larry – thanks for your fast answer. I live in Switzerland. Can I find the correct cable here or can you ship ? Cost ? – also how difficult is it to install ? I have figured out how to remove the iMac glass screen (yea!) – but do I need to (completely) remove screen and connectors too ? am a bit anxious…

  • Hi, I have a 2009 macbook pro that the Hard Drive mechanically failed in, and I have a 2010 macbook pro that the logic board failed in. I’m wondering if I can use the 2010’s hard drive in the 2009 machine? The 2009 is mid, and still is the 2010. The 2009 has a core 2 duo, and the 2010 has the i7. Please let me know if this is possible without compromising the data on the disk, or locking permissions. Thank you

    • Hello Freddy,

      Using your HDD from your 2010 MacBook Pro in your 2009 MacBook Pro will be 100% possible. This will not compromise the data on the disk, or lock permissions.

      Please contact our Technical Support Team if you have any further questions!

  • . By the way I reset the Pram & SMC just in case to. I am not sure it makes any difference but it seems to be going very well and as I said super fast . I love this Imac and can only see greater potenial when conparing it benifits to the new MacPros. In many ways it has so much more to offer & I believe worth more than a mac pro . Iam not surprised Apple didnt put larger hard drives into there machines. Its would for many make it a no brainer to be Imac instead.

  • Anyone else who has tried this upgrade or similar let me know please how you went. By the way I reset the Pram & SMC just in case to. I am not sure it makes any difference but it seems to be going very well and as I said super fast .

  • 7 TB IMAC I7 UPGRADE . In relation to installing new hard drive( 2011 i7 27″ ) & placing solid state drive behind the ODDrive.Just for information a few days back I replaced the original 1TB Seagate drive with a 6 TB WD green and placed a 1TB Samsung behind the optical bay. I used the OWC kit for each. I am not an expert and it was the first time I have attempted iMac surgery, I must say it was easier than suggested but watched the OWC videos about 20 times first.. Secondly just to be safe I have also purchased the Tunabbelly temperature gauge app which gives 28 different temp sensor readings. This appears to to be very useful as I can see other readings such as the power supply which can be a great source of heat in an iMac 2011 . I ran it for a few days but as I am unaware of the true temp parameters for things other than the hard drive I have also installed the HDD fan controller software which seems quite flexible in adjustment parameters. Before using HDD the fan was not running too fast but just in case something else was causing excess heat i thought it better to play safe and use HDD as an extra precaution. I don’t know of any one on the net with a 7 TB combined drive to date. I have 2 X 16 TB Promise Back ups for my photography but was forced to increase my internal & would nearly fill the new 8 TB but will install that lf all goes well here . I failed to say in my last post it is running super fast all seems well . My only questions is waht is the normal operating temp for the power supply? as this is seems to get up to around 70 C after several hours of use or when using heavy applications ? If anyone can direct me to the various normal temp parameters for this model it would be great. I am also not sure if the HDD control works on the other fans but I feel it does not. Anyway the Hard drive is runing cool with the HDD and the ODrive O seems god too. So as long as something else isnt happennoing unknown it seems to be flying. Wish me luck.

  • Hi, I purchased your HDD replacement kit for imac 2011 27″. I had previously installed 2 SSD drives – one behind the optical drive and one in an Icy Dock, replacing the original hard drive.

    Due to the constant fan spinning, I purchased your thermal sensor cable. I installed it now. I also replaced my optical drive with an ssd and your optical bay mounting kit.

    Right now I am stuck at the apple logo and the imac refuses to continue. It just stays at the apple logo with the spinning gear wheel underneath.

    What could be preventing the boot? I forgot to mention that prior to the install I had my 2 drives in RAID 0. I tried booting into Recovery Mode, tried booting with Alt pressed (so I can choose to boot from an external clone) – all to no avail.

    Can you help, please?

    • Sorry to hear about the issues. Being stuck at the Apple logo means something in the OS got corrupted. Since you have a RAID 0 configured there will be no recovery partition on the computer, so you’ll need another drive with a recovery partition or that has an OS to boot to and attempt to repair the corruption on your startup disk with Disk Utility.

  • Please excuse my lack of experience and I am so sorry if this information has been addressed already, but I phoned Apple today and they told me my machine cannot have additional RAM installed once it leaves the factory? They said only the 27.5″ of this model could? It doesn’t make a lot of sense to me but is this really the case? Thank you so much for any information you might provide. I’m really bummed as I’m maxed out and my once perfect machine is now dragging……

  • Can I use a 3TB HD in a 2011 Imac?
    If not how about a partitioned 3TB as 1TB/2TB?

    • You may install a 3TB drive into a 2011 iMac. We offer a DIY solution for adding any make or model HDD if your iMac is a 21.5″ iMac 2011.

  • Hi, i have a mid 2011 27′ 3.4Ghz 2GB graphics 16GB ram 1TB HD, I purchased the following OWC Kit’s OWCDIYIM27HDD11 & OWCDIDIM27SSD11 a few days ago. I removed the factory fitted HD and with the help of the OWC DIY video which for me was a great walk through and to be honest it’s not so hard to upgrade a iMac as i thought, I put 2 SSD units ‘Sandisk 480GB one on each side of a 2-1/2 Inch HD back plate adaptor where the stock HD was and did not need to put one SSD behind superdrive, the thermo’ sensor that’s in the kit I placed it on the top SSD drive and does the job perfect also no fan issues then i put a fresh install of OS X 10.8.2 in RAID0 and all is well Amazing piece of hardware super fast i installed the full CS6 Full suite in 8.13 sec it’s like having a Ford Fiesta and trading it in for a Bugatti Veyron’, the only problem i have come across is when i use Black Magic Speed Disk test its giving me the following READ Speed of 979 & WRITE Speed of 419 now i am not happy with the Write speed as it should be somewhere near the Read speed as i have seen some post’s of others on the web doing a similar upgrade can someone please help me out so i can get equal Read & Write speeds, i also have some pics of the upgrade if needed by anyone…

    • BlackMagic uses incompressible data in its testing. On a SandForce-based drive, this would report lower speeds, since the Durawrite technology used in the Sandforce controller compresses data in part to achieve its speed. The BlackMagic test is good for a worst case scenario of write speeds. We’ve found that the QuickBench Speed Tools benchmark (which uses compressible data in its testing) shows more accurate speeds for the average user.

      BlackMagic does performance testing to help determine suitability/capability for various video-related functions. Raw video capture deals with compressible data… whereas conversion and editing of already compressed video file types is dealing with incompressible data. If the purpose of your benchmarking is for the optimization of a video production workstation, then BlackMagic would be the test to use – for most other purposes it isn’t going to give real-world results.

      • HI Michael I have just purchase Quick Bench and done some tests and yes you were correct after several tests on my iMac I am getting the following results – Extended Test (20 – 100MB) with 5 cycles
        Extended Test Averages –
        Read Speed 1040 MB/Sec
        Write Speed – 950 MB/Sec

    • Hey Mario, Enjoyed your comments on the OWC blog about replacing your imac HDD with two SSDs, as this is exactly what I’m doing for my mid-2010 27″ imac. You said you had some pics of the upgrade which would be really helpful, especially concerning the thermal sensor, which is the last bit of info I need; your expertise on this would be greatly appreciated. How and where does this hook up? The pic of the kit looks like (along with the sensor), there’s a SATA power on one end (male/female?) and a male SATA data on the other end. I’m assuming you also used (not pictured or mentioned) a single SATA cable for going off the motherboard and a SATA power splitter for the two SSDS to be hooked to the imac’s one available SATA power connection. Correct?
      I could really use your help on this as I’m chompin’ at the bit to get my blazing fast Samsung 840 Pros installed and RAIDed up.

      • Hey Graydon
        Thanks for you kind words, now you have a mid 2010 now from what i know there is some changes in my mid 2011 1st Q -you want to know were the thermal sensor goes i have added a link below so you can see were i have placed it and you would need this cable OWCDIYIM27HDD11 , 2nd Q. the single SATA cable that came off the original installation of the HD was not removed i just added the power cable mentioned above thus together i was covered for the one SSD HD, now the other SSD HD i purchased the following cable OWCDIDIM27SSD11 that is shown in the video for installing behind the optical drive which i did NOT and put both SSD’s were the factory fitted 1TB HD was on a custom made plate the wires were long enough for me to carry out the above mentioned and NOT having to remove the optical drive and it’s fan and place the second SSD behind no need. NO power splitter was used because both mentioned kit’s above one is DATA & Power and the other is just Power with the thermal sensor, my opinion on the SSD’s that you want to purchase they are great but i think to expensive check out my link and you will understand why I used SANDISK 480Gb 6.0 Gb/s they are very similar in speed as you will see in QuickBench test’s i run you will save a easy $500 if you purchase two units because believe me my iMac fly’s and don’t listen that RAID0 is unstable i guess it is on windows but not a Mac :) using time machine or like i use Drobo you will be covered in case something goes wrong which i very much doubt. so here is the link i hope it was of some help to you sorry i could not get to you earlier i was on a business trip and got back yesterday and please let me know how it got on or if you have any more quires let me know and i will try to help you out if i can.

        • While we encourage the DIY philosophy, please note that the 2011 HDD thermal kit referenced above is for 2011 iMac models only and not designed nor supported for operation in the 2010 iMac.

        • Hey Mario,
          (Update) Thanks again for your info. Just to let you know, the installation went fine and everything working perfectly. (I used an apple 2010 optical thermal sensor I ordered to replace the one removed and there’s been no fan issues.) Over a terabyte of completely quiet SSD power RAIDed together internally is just so much fun; no bouncing app icons in dock when opening 5000 photos or 600 gigs of hi-def video, it’s just all…there…instantaneously. This kind of upgrade along with using conventional hard drive external mass storage and backup makes my iMac an instant classic and upgrading to a new one a non-issue. (no Thunderbolt or USB 3 ports on this model doesn’t bother me at all; Firewire 800 is more than adequate for externals as long as the inside is roomy and blazing fast, which it is!) Thanks again, Mario, and happy trails.

          • Thermisters like the one from the 2010 iMac for optical bay are NOT compatible with the Apple iMac 2011 SMC.

            Apple custom firmware on factory drives outputs a digital signal that provides SMC with the HD temperature information so it can control fan speed. The thermistor(apple 2010 optical thermal sensor ) you installed simply shorts the line in the 2011 iMac when installed as you have done. Unlike the digital thermal sensor we provide in our 2011 iMac HDD upgrade kits, a thermister is effectively makes use of a resister that varies in resistance to depending on temperature which a system designed to use such then determines temperature by voltage level.

            why does what you did seem to work? Because you can also get the iMac with only an SSD inside. And in such case where there is no HD present in the HD bay, Apple instructs that this thermal line be shorted to tell SMC no HD present and nothing to monitor – which results in the fans never going above the minimum.

            As you have two SSDs installed and no hard drive (if I understand correctly) – there should not be any issue with heat, but just be aware that there is no temp monitoring the way now setup. Again, the Apple thermister installed is doing nothing more than a straight wire connection shorting that sensor line.

            hope this helps.

            • Thanks Larry,
              This optical temp sensor solution was arrived at because I was out of options. Your people at OWC were very helpful but would not (a.) do the installation for me since I was using non-OWC SSDs (understandable, although I very much wanted this in the hands of your capable and experienced people), or (b.) give me any info about your digital thermal sensor solution (what resistor), or even sell me one (also understandable since this is part of your in-house custom turnkey program). Ditto with certified Apple repair people; the information was just not forthcoming. So to just ‘get on with it’ after 8 weeks of research, I knew this would either work or, at the very least, just short it out so the fan wouldn’t ramp up to full speed and I could later download smcfancontrol if needed. Since the SSDs don’t have heat issues it was a pretty safe bet, although I obviously wanted it to actually function correctly in the same way OWC’s thermal sensor solution would. Thanks again.

                • Thanks Larry,
                  One more quick question to you. Did I understand you to say that after substituting an optical temp sensor in my 2010 model I have no fan response at all (even in a critical heat condition), or that the fan can only run on the minimum speed? And if so, does it run continuously or what? (the confusion about this is because the comments are intertwined about 2010 and 2011 model differences). And lastly, should I download smcfancontrol (to get S.M.A.R.T. monitoring) or risk not having any fan when it’s critical? Basically, what’s the story with my fan’s functionality as it now stands in my 2010 imac. Thanks again, Larry.

                  • I sincerely apologize – my posts were based on your upgrade having been performed in a 2011 model iMac vs. a 2010.

                    The 2010 does use the thermister type feedback and you’re fine with what you have done. Disregard the SMC disabled as that applies to the 2011 when you short the line and not the 2010 iMacs.

                    • Thanks so much Larry for the quick response, that’s great. I want to say how much I appreciate you and the people at OWC, your customer support, great products, and tech support, not to mention this excellent forum you’ve set up. Just stellar. Thanks again,

  • Hey Larry,

    You´ve come up in my Google search as a true angel, because I´ve been looking for weeks to solve a couple of mysteries I can´t seem to solve.

    Here goes…

    1. I totally agree… this iMac is the best iMac ever! As I found on your “Apple´s iMac 2011 Model Hard Drive restrictions” blog, I have been reading it
    once and again in order to understand what Apple has implemented on some WD Caviar Black Drives in order for temperature to be “read” by the Hardware.

    I have upgraded its memory to a full 16GB of memory as I use my iMac for Professional Music Production. I got a ADATA SX910 512GB SSD in order to be the
    boot disk and store my Lion system as well as my Sampling Library (which I need to be loaded really fast). So I opened the iMac and pulled out my Caviar Black HDD
    and replaced it with the ADATA SSD. Every thing went great except for the “fan issue” which I corrected with the HDD Fan Control application.

    Everything runs great.

    I removed my Black Caviar HDD and put it in a Thermaltake Docking station in order to load more sample data and music sessions.

    Everything runs great. (haha)

    The thing is that now I ordered a 12.7 mm SATA Optical Bay SATA Hard Drive Enclosure removing my optical drive, and plan to put back in my HDD and put my ADATA SSD inside this caddy from iFixit. And return my HHD to its original place for document data.

    Now that I removed (and kept) the cable that goes onto the jumper section of the HDD, I want to put back my HDD for document files, and run with the SSD and the HDD, but don´t know how to insert the jumper cable… I mean, which jumpers are needed to be bridged. I am afraid to connect those in a way that might reduce the data transfer speed to 1.5GB/s
    Can you tell me which of the four positions of the connector should I use? (upwards left, upwards right, downwards left, downwards right) or maybe just tell me which pins should be bridged with the cable?

    2. The second thing is I just read that these iMac have 3 SATA ports, and would LOVE to put a third drive (SSD) on my mac for video playback and storage. I assume port number one (no particular order) is for the Optical Bay, number two for the HDD and a third for the SSD option from Apple. The question is, does my iMac has this empty SATA 3rd port? Because I don´t want to open the thing up to that point (which I read is pretty hidden underneath the motherboard). You would save me a few minutes! hahaha…

    Thank you very much for your assistance, I promise I´ll keep you posted on my Soon-to-be iMac Turbo. :D

    Best regards!!

  • Interesting how you won’t show a picture of the Apple Manual that shows how to short the 2011 HD sensor due to “copyright restrictions”, but you will show the same manual’s copy of the license agreement you claim does not void Apple’s warranty if a user opens up the case of an iMac.

    But I digress….so you buy the Gravis solution but don’t sell the outright and only install them in iMacs that someone sends to you for doing it themselves? I emailed to buy the part and tech support said they don’t know about the Gravis solution and don’t even offer a turn key solution to ship to them to make a 2011 iMac work on only a SSD. You’re own tech support doesn’t know about your program.

    So I give up…I was going to buy part APPLE 922-9628 CABLE, JUMPER, HDD TEMP SENSOR for the 2010 iMac and short out the HDD Sensor but heard from others it either doesn’t work or will still FAIL the AHT. I’ll just leave my SSD in there and run the Apple Seagate with nothing on it. Sad….but if you are telling and have not updated the board in months that means you don’t know, the Gravis failed or you stopped selling it or worst yet they all fail the AHT and screwed. I love/hate Apple so much. It’s like an ex-lover you can’t stop thinking about but know in your heart why you dumped her.

    • Will try to respond in order of subject….

      The Apple documentation regarding the SSD only config and short for SSD only config is not part of a publicly available document. That is the difference regarding this vs. the other user manual information which is publicly available.

      The complete solution for using a non-Apple hard drive properly and reliable in the 2011 iMacs is actually close to being part of a kit we will offer. You will be able to purchase that kit within the next 2-3 weeks in fact. We currently do not offer a program to convert an iMac that has a drive and SSD to SSD only at this time – although we do offer through turn-key the option to replace an existing hard drive with an SSD.

      The 2010 iMac used the standard hard drive thermal sensor output for SMC temp monitoring. The problem though is that WD, HGST, and Seagate all have different size pins for this connection. Apple uses multiple OEMs for the drives… If you’re 2010 iMac game with a Seagate drive – you can replace/upgrade with another Seagate drive and all is well, HGST for HGST, WD for WD. For Apple – this does present a bit of a servicing challenge for drive replacement or requirement to maintain stock of all brand OEM drives. We have a thermal sensor that takes the place of this for 2010 HD upgrades.

      The 2011 iMac – we’ve covered that in the blog. Apple did something very different and completely non-standard by using the drive activity line that is part of the HDD Power connection harness to communicate the thermal. This is totally custom firmware on the hard drive to re-task the drive activity line to instead send temp pulses. It eliminated the need for Apple to have an additional cable, that had to be MFR specific, going to the hard drive… but now – take that drive out, and your fans rev. Put non-Apple firmware drive in – and your fans rev cause it doesn’t have the firmware doing temp data. Yes, we have the reliable solution for replacing this with an external device – and soon will have packaged for DIY as well…

      Apple doesn’t do these things to make it easy for upgrading, they do it to make it easy for their goals..

      Do at your own risk and assumed understanding:
      Now – if I read right, you just want to remove your hard drive – run only with an SSD? If that is the case, you need only short the thermal lines (what normally would be HDD Activity lines) after removing the drive – can modify the cable you disconnect from the HDD to accomplish this. Sounds like you do know which lines we’re talking about and that will tell the 2011 iMac (doesn’t work for 2010!!) that it is an SSD only system and there is no HDD to control fan speed/temp for.

      Feel free to contact me at for further assistance or information.

    • Hi please check out my post i put up yesterday it might be of some help to you, I upgraded my iMac and now it’s running on just 2 SSD’s flawlessly,

  • I have the mid 2011 27″ iMac with a factory SSD and a factory 1TB HDD for storage. I want to replace the 1TB HDD with a 3GB HDD. Can I do that without worrying about what drive I put in or what firmware it is? I don’t know if both drives are being monitored, just the SSD or just the HDD.


    Remove the HDD board from the Bad HD and Plug just the Sensor Cable and It’ll act like a Sensor.
    It Worked Like a Charm for me, i Tried using one Sensor for both HDD and ODD but all fan’s went Crazy,

    When i tried removing the HDD Board and Plugging in as a Sensor it was Quiet and Smooth.

    Guetto Style Baby :P

  • So how long will we have to wait for a TurnKey Program for the 2011 iMac to install a SSD and a 3TB HDD?

  • Hi OWC

    The new iMacs with pre-installed SSDs have been ot for a while now. Anyone had a chance to see how they’re fitted / connected etc and to pass AHT and give a temp check?

    Any further updates regarding possible SATA data and power cables to feed a DIY install of a new SSD with existing preinstalled HD?

    Many thanks


    • Our development team is hard at work determining what we’re going to be able to offer on these machines.

      As a general rule, OWC does not release products or services until we’ve put everything through its paces to insure we’re offering the highest quality product we can. While that diligence can take some time, we feel it is much better in the long run to choose quality over rushing a product to market.

      If all goes well, we’re intending to have something in the next few weeks – unless of course we get sidetracked again by Apple releasing several more machines and another new operating system. ;-)

  • Hi Folks,

    Spoke with Travis today concerning the possibility of you folks performing a “turnkey” upgrade to a new 2011 iMac 3.4GHz…but with a twist…

    The mod I’m looking for would be for two ESATA ports installed so that I can create multiple RAID setups. The idea here is to have the computer being able to boot both Snow Leopard and Lion to run both FCS 3 HD and FCPX respectively. 10.6 can be booted from an external FW800 drive (more than enough for what I’m looking to do) and 10.7 from the internal HDD…of course, that it is possible to swap out the internal 3GBps II drive for a 6GBS III drive, that would even be more awesome! And, what would knock-it-out-of-the-park is if one of the external ports could now be 6GBps III…!

    I have correspondence out to the folks who produce HDD Fan Control to see if their software would mitigate the run-on fan issues with this setup…waiting to hear back.

    The goal here is for a dual boot iMac CTO 12,2 with FW800, 2x ESATA (from OWC), 2 Thunderbolt ports, 2TB 6GBps III internal startup drive (from OWC)…

    …I’ll be more than happy to supply the machine and third party software…you guys and gals game?!


    • Hey Jimmy….OWC is known for innovative products and services…so yes…this custom “twist” can be done….but lots to discuss and consider so we’ll be reaching out to you directly then to continue discussion on this.

      • Hi Grant,

        Thanks so much for the speedy reply to this, I do appreciate it!

        I did generate an internal pre-sales info request with you folks on this matter (you can find all my contact info there!) and updated that information this morning after corresponding with the folks over at HDD Fan Control…

        Looks like their software will properly control the S.M.A.R.T. thermal functions of the iMac to allow for this mod to work properly without the fans running-on.

        Looking forward to hearing back from you! :)

        Best to all,
        Jimmy G

        • We are not a fan of the software solution for a couple reasons… The most significant being that if the software becomes disabled or isn’t re-installed after a system wipe/reinstallation – you end up without proper cooling of the hard drive bay – which is a problem if there is a hard drive in the bay. We are testing an electronic solution that retains the Apple SMC monitoring function with non-Apple firmware drives. As long as this works, won’t need to depend on software that takes processor/sata bus cycles and could be forgotten by a future owners, etc down the road. :)

  • @OWCLarry

    What was the outcome here? Is there an OWC kit/cable/etc. in the works? Or further description?


  • You note that the pulse intensity varies from brand to brand. It may be that the temperature is being indicated by something other than the intensity of the pulses.

    For example, it may be that the frequency of the pluses is what is used to report the drive temperature. As the temperature changes, the frequency of the pulses (or the time between them) may change. This has the advantage of being more resistant to background noise than does a simple voltage output signal. (Voltage to Frequency Converters and Frequency to Voltage Converters are frequently used in Industrial applications for this reason.)

    It may also be something even more creative. Perhaps the duration of the pulses. Or if there are different kinds of pulses, it could be the relative positions between them.

    The above is assuming that the drive is reporting the actual temperature. If it is simply reporting a binary condition, that the drives are OK, then it may mean something different. But I wouldn’t expect an Apple design to be that crude.

    Hope this helps.

  • Hi everybody!

    I’m waiting for my iMac 27″ 2011 model to be delivered. And have bought an SSD to upgrade it. Is there a guide on how to install the SSD without compromising the Primary HDD?


  • Does the fan speed and all the other problems only exist if I replace the main HDD with another HDD or SSD ?

    so if i just want to install a SSD in the SSD bay, there is no problem ?

    • Correct, the issue is with removing the main bay drive – adding an additional SSD caused no issues.

      • I kinda missed that detail before… So, I could order an iMac with a 2TB drive from Apple (not my first choice, but until the HDD work is complete, that’d be my choice right now — I really want a 3TB drive in there), and then have a 6G SSD installed from OWC? Can you also put a 3G SSD in the optical bay?

        If that’s all do-able, then maybe I don’t need to wait on the new iMac after all.

      • So if that’s the case, are you able to install SSDs in the second drive and, if so, when will that service be available?

    • hey Robw…we’re actually talking to Gravis and moving along same path with a solution.

      Their single source solution sounds very promising, but we’re cautiously optimistic since 2011 models have different reporting requirements.

      The voltage signaling on the 2011’s is different than 2009-2010…so hard for us to understand how one solution addresses all models. From our experience, solutions that work for 2009-2010 disable 2011 hard drive bay monitoring.

      Make no mistake…this is exciting news that an external monitoring module can replace the drives’ internal sensor…even if just for the unique 2011 models. Further testing will confirm whether this truly address 2009-2010 models too.

      • I can further add to this… We have been working to the same ends and happy to work with anyone with a solution already too. We’ve done extensive testing and while replacing a hard drives standard thermal sensor capability with the external module is a solution on the 2009 and 2010 iMac for HDD bay – as is properly connecting to the standard pin outs for the thermal sensor that is built in to most 2009 and later introduced hard drive models – there is a little more to it with the thermal line voltage signaling on the 2011. Otherwise – it would be a solution to simply connect up to the standard thermal sensor lines on hard drives, more challenging to do with the wiring in the 2011, but a solution none the less. We have a ‘cutless’ solution for bypassing those lines out in the 2011 model, now just need to complete the external thermal solution which will ‘talk’ the Apple needs for the 2011. If Gravis has that solution + it’s got some intelligence built in to switch/support the 2009 and 2010 models too (which becomes convenient then) – absolutely fantastic! I am currently in contact with them and am excited to see their their module work.

        • I’m glad to see OWC and Gravis working to figure sound solutions to this issue. Where is OWC’s solution for the glossy iMac screen? I’m sure many would love to have the matte screen of the MBP on the iMac. ;-)

        • Hi All

          Any further updates to this blog :-) I see that the imac 2011 are now shipping with SSDs installed. You guys had a chance to review their internal workings for a possible way through to getting one installed whilst not interfering with the pulses from the existing HDD?

          I and many others are eagerly awaiting more news

          Many thanks for your work so far


  • @OWCLarry

    I’m a DIYer but having trouble following the discussion.

    “That’s what we got so far… Pretty sure all the non-Apple HD upgrade reports where all is well have also done the SSD too with the y-power… so – hopefully all this discussion will help save some drives.”

    Does this mean that if all you want to do is swap the main HDD with an SSD and use software to control the fans, AHT will pass and you’ll otherwise be OK?

    If so, could you provide a link to the required hardware / process? Just a y-splitter?

  • I’m sure crossing my fingers on all this working someday soon. I’m gathering my funds for a new iMac, and would love to have it upgraded with a 3TB internal drive for media storage, a “slow” SSD for the OS, and a “fast” SSD for my Aperture library.

    I’m definitely staying tuned!

  • From the iMacs, these model drives were found present in the systems we received:

    Seagate ST3500418AS 500GB 7200RPM Barracuda 7200.12 7200RPM 16MB SATA 3Gbp/s
    Seagate ST31000428AS 1TB 7200RPM Barracuda 7200.12 7200RPM 32MB SATA 3Gbp/s
    Western Digital WD1001FALS 1TB Caviar Black 7200RPM 32MB Cache SATA 3Gbp/s drives in which models.

    Can you please tell what drive came in which model? like the 27″ 3.4Ghz Thanks

    • Seagate ST3500418AS 500GB 7200RPM Barracuda 7200.12 7200RPM 16MB SATA 3Gbp/s: was in the 21.5 2.5GHz

      Western Digital WD1001FALS 1TB Caviar Black 7200RPM 32MB Cache SATA 3Gbp/s: was in the 21.5 2.7GHz and the 27″ 3.1GHz and the 27″ 3.4GHz

      Seagate ST31000528AS 1TB 7200RPM Barracuda 7200.12 7200RPM 32MB SATA 3Gbp/s….note was a typo in part number….was 428AS….now corrected here to 528AS….was in the 27″ 2.7GHz and the 21.5 2.8GHz

      and there ya go!

  • One can only speculate, but I assume the reason Apple does NOT use SMART temperature data (and has a separate thermal sensor) is that the thermal control of the imac is performed by the SMC Controller, a completely separate micro-controller. The SMC DOES NOT have access to the SATA data lines and therefore can’t read the SMART data. And you really would not want asynchronous SMART commands in the middle of your data transfers :o)

  • Two items …

    The 27 inch iMac I have (2007) came with the AHT on CD, I believe it was, Tech Tool Deluxe version 3. I upgraded to what is apparently still the current version – TechTool Pro5 5.0.7.

    Both versions are still broken.

    They don’t report disk failures… even though a drive fails their tests!

    I had a drive that would not spin up … and both Apple’s Hardware test disk and the one I purchased as an upgrade, passed the system — even though it failed all the drive tests because it could not spin up the drive!

    One wonders if Apple has replaced the software they use for their AHT.

    Second… to check temps and drive/fan speeds — I use iStat Pro from Bjango — It’s a dashboard widgit as well as an iPhone/iPod app.

  • hello! I read about smart little freezing drives for a little time… therefore apple probably wants overcome this little accident to improve constant access and fluency… thanks

  • has this test been done, as I do not have an iMac yet

    These parts (from this website 9229216, 9229217, 9229215, for sensing the temperature. My theory is that the white wire (black is probably ground) is now PIN 11 by using the custom firmware. I would like to propose that PIN 11 on the SATA power connector be connected to where the white wire is connected normally using this cable.

    As I said – its complete theory from reading so many posts and not having my iMac here to look further…

    If I had my iMac I would measure the voltages first and do this test and provide results here, but my iMac is currently being loaded into a shipping container and I won’t see it for 8 weeks….

    • We actually have a few interesting test scenarios in play today to get a better understanding of how the thermal data is being communicated with the new scheme. We still have hope for a solution that will keep the Apple thermal monitoring and fan control operational while allowing a non-Apple Rom HDD be installed into this bay.

      At the end of the day….

      I for one am not overall thrilled about needing to depend on a 3rd party add-on to maintain hdd bay temperature if the Apple factory drive is replaced with another drive. Can still add an SSD to the SSD bay without issue (using a cable solution that doesn’t close that thermal line… otherwise you’re still shutting Apple’s fan control down on that bay and likely going to early cook a drive) and that may be the best choice until a solution maintaining standard Apple built-in HDD bay thermal monitoring and fan control comes along… either by something Apple does or a firmware option for non-Apple drives.. or some hardware trick, something we’re testing a couple bits for now. All this stuff is do at your own risk and those who work in iMacs know this. But where user data is in play, and regardless of backups (which you should always have anyway, but timing can be everything), so thought on the matter is justified. :)

  • OWC Larry,

    Thermal design has been an issue with Apple Computers as long as I have been using them. Some of them were simply horrendous. Frankly, I believe that the “industrial design” (styling) crew have been guilty of creating enclosures and then leaving it to the engineering team to make the best of it they can.

    The rather obvious question which appears to have been ignored by Apple and everyone else is just how often does the temperature of the hard drive need to be addressed? Without knowing the precise answer, I would nevertheless be surprised if it were not a lot less frequent than Apple have actually sampled. The bandwidth issue described in the HardMac article could be expected to cause problems and yet Apple used the SMART based system, probably because it saved the cost, however small, of an external to the HD sensor. Apple would not be the first manufacturer to cut corners for the purpose of reducing costs a few cents per hundred units.

    The problem here is that the current design leaves one entirely dependent upon Apple for one of the most basic parts of the computer which is also the most likely to need replacement because of failure. It does not leave one with a warm fuzzy feeling.

    • Agreed 100% with regard to iMacs and thermal issues. Of our 98 iMacs (2008 24″), we’ve had 25% suffer HD failures. All of those seem heat-related; they will often work for 5 minutes when cold and then fail. For the remainder, I’ve installed iMac fan control and ramped the fans up to 3000RPM minimum, and the failures have tapered off. These units get HOT under completely normal conditions and it very much seems as if Apple favored design and quietness over preservation of components. We’re due for a refresh soon and I’m very concerned that we’ll not be able to swap the HD’s in the new 27″s as we are able to now with the 24″s. I mean, even if we succumb to the idea of having to pay 2x as much to buy Apple-ROM’ed HD’s, Apple won’t sell parts to anyone but authorized service centers, so we’ll also have to pay someone else to install them even if we have the know-how. This is pretty much unacceptable in enterprise and something we’ll need to discuss with our Apple Rep. before they get any more sales from us.

  • I have a question about these new drives that I am hoping someone at OWC can answer.

    Lets assume I buy one of these new iMacs, and a few years from now the machine has a hardware failure (not drive related). Can I pull the drive out of the iMac and get the data off it and/or use the drive on a standard SATA connection in another machine? In other words, will these new iMac hard drives work like standard SATA drives in other computers, Mac or Windows based?


  • Hmmm. It just so happens that a few days ago, I replaced the Seagate Barracuda 80-GB original HDD in my old early 2005-vintage iMac G5 with a Seagate ST3500418AS 500GB Barracuda 7200.12 HDD, and it works just fine.

    Not being able to easily upgrade a HDD in a new iMac would put me off from THAT model. I guess that instead, I’ll someday get a Mac Mini–assuming that a HDD changeout is NOT a problem with THAT model–and patch it to a monitor via a KVM switch along with my Linux OS PCs. . . .

  • What is the physical configuration of the power connector? A standard SATA power connector has 15 pins, and *none* of those are unused. It’s three each of 12V, 5V, 3.3V and two sets of three GND. I would imagine the drives either replace one or two of the 3.3V or GND connections with the thermal sensor leads. It could also have a few non-otherwise-existent extra contacts added but that would be a *really* expensive solution.

    This is wacky, and not remotely likely to become an industry standard. As you say, industry standard is SMART monitoring. Disadvantage there is that SMART monitoring doesn’t work when the drive is depowered. I suspect that that’s the issue — Apple wants to keep thermal issues verifiably in check even in full standby.

    Given how wacky it is, it will require not only a new PCB for the drive in question, but probably an extra component if it is to be software-switchable. Given the cost of the latter, I would expect that the regular drives will not be software-switchable to apple configuration, and that apple simply gets models with a very slightly different pcb and 2 extra traces.

    Assuming that the temperature sensor is electrically compatible with the regular jumperblock one, though, it should be possible to manufacture a) drives that work (by soldering a few wirewrap wires to them and cutting the traces those pins normally go to), and b) adapter that sit between drive and powercable and wire up to that jumper block. If this temp sensor is radically different, we’ll all have problems.

    • Will have a new entry soon with greater detail, but this isn’t a custom PCB on the HDs. Apple has apparently re-appropriated the output lines for the drive activity indication (drive an LED, signal for an LED, etc) and via firmware enabled a method to use this for the thermal sensor feed instead of using the pin connector for this, which is different for each drive mfr brand. It’s firmware enabled on what are otherwise standard drives by all appearances. Of note is that the voltage on the line and the pulse range was different between the two brand drives we pulled from the iMacs. Again – we’re digging in on this. Just some time.

  • Thought I might add some more perspective – even in light of hd work around…. In the 2009 and 2010 iMacs where the thermal sensor first became an issue, it was not a big effort to maintain the functionality of the thermal reporting for the HDD bay.

    In the current moment, any solution that involves a non-Apple hard drive in the HD bay means that iMac no longer has standard operation. 3rd party software is needed to maintain proper cooling via fan speed control. This software will need to be maintained during OS updates, reinstalls, etc. If the iMac is sold, the buyer will need to be informed so they don’t inadvertently toast the drive too.

    This is less than ideal – workable – but has potential for greater consequence down the road. I hope there is a better way…. Otherwise – adding an SSD and leaving the Apple HD may be just as well. We’ll certainly have the right solution for that – including correct cabling, etc.

    • Look at Apple’s service manual, Larry. They short the pins themselves if you buy the iMac with an SSD.

      Here’s a screenshot from page 226, if you guys don’t have the manuals yet:
      (link removed by OWC editors as this would be copyright infringement)

      This is the solution everyone (besides OWC) has been using on these models all along, and Apple is using it too. I think you’re probably safe to go ahead and accept it as-is for SSD use, and toss in some S.M.A.R.T.-based monitoring for more heat-producing drives, although I usually recommend to people that they use the software monitoring for SSDs, too, just out of an abundance of caution.

  • Having read the Hardmac article, I am further convinced that Apple should make this a non-issue by providing the firmware to anyone, including end users to flash the drive firmware on appropriate drives. Indeed, if Apple were to “open source” the firmware and use of the #11 pin for temperature sensing rather than an activity light, it just might happen that the industry would adopt the idea. After all, there are other ways that activity can be inferred. It would not be necessary in all applications.

    The way things stand, it seems to me that this is an additional reason to not use the Apple (rotating) internal drive and simply run TB external enclosures in conjunction with internal SSDs.

    All else failing, I suppose that someone will download the firmware and work on a solution for SATA 3 drives, but the problem there is that the manufacturers will continue to change the firmware of their drives requiring an ongoing project to hack the firmware.

    What a PITA. Apple could easily have continued to use an external to the drive temperature sensor, but nooooo, that’s too simple.

    • Unfortunauntly, Apple never released the 2010 firmware and is really unlikely to release this either. They take VERY arrogant stances on issues like these.

      I do have to disagree with OWC on the fact that you just needed a drive of he same manufacturer with the 2010 models. This is definitely not true. Each drive manufacturer had specific Apple firmware and Apple would not release it. Neither would the manufacturers. It’s a shame that Apple is going back 90’s. This is good for windows because major corporations will continue to say away from mac when proprietary hardware is enforced. This is Steve Job’s downfall.

      • For the 2010 Apple iMac models, there was no operational impact to using a non-Apple firmware HDD in place of a standard drive. Once your past the main barrier, getting inside the iMac, just needed to make sure you had the same drive brand as to be able to connect that thermal sensor line (each HD manufacturer has their own pin set, that’s why I believe Apple sought their 2011 solution for the single connector) or have an alternate solution which would still keep the thermal sensor line active and the fan speed controlled for the bay. Otherwise, no different than putting drives in a Mac Pro – operation was normal regardless of Apple firmware or not.

        2011 – Apple’s got custom firmware that re-appropriates a line on hdd power connectors for the thermal sensor data. That’s a whole new ball of wax. We still have testing to do… but it doesn’t appear that just taking that line off and putting a thermal sensor on it is going to work as the line doesn’t appear to work the same way in the 2011 implementation.

        We’ll see… but this is a new and more unique barrier. Right now the barrier can be overcome effectively with a combination of a simple hardware ‘fix’ along with a software solution… but, as I have commented a few times, it is less than ideal to be dependent on a software add vs. the standard, stock built-in system which the user needs not be watching and wary of as future software updates, etc come out and/or just general bugs/unforeseen glitches, or even accidental disabling.

        • It may have been them case for the WD and hitachi drives but every Seagate I upgraded had a APxx firmware and even with the correct connection, it still revs the fans after 30 or so minutes. I have mc508 and mc510 models that I can recreate the issue today. It was not as simple as the same drive manufacturer. I contacted Seagate to get the firmware, and was turned away as it was only available from Apple.

          • Could be a model generational difference, it was more recently that manufacturers added the support for that thermal bit on the pin outs. We did a lot of testing and have machines running here as well with Seagate non-apple inside and that’s the only reason we put that hard drive compatibility info out there for the 2010s:

            If you have a chance, feel free to fire email to concerning the model(s) Seagate p/n that still had the revving fans in the 2010 model. Also if the original drive was a Seagate or a WD.

            And as to the firmware, you are absolutely right there… Apple doesn’t share and has no motivation to share that ever. The one hope that still exists concerning the 2011 issue is that it is possible that the drive manufacturers could (long long shot IMHO) release a firmware option for drives to do what the Apple firmware does for that thermal line output. It isn’t anything different in the hardware physically on the hard drives that make this possible, it’s all in the drive controller software/firmware that’s enabling that line out. it’s a long shot though as drive makers and most manufacturers like sticking with common, tried an true, mass production solutions vs. variances that can come back and bite them. Further… unless there is an application need/demand/benefit outside of these iMacs, never going to happen for very obvious reasons.

  • I’ve been using SMART for quite a few years, and am using it on my Mac Pro currently. While this is a helpful indicator of the drive’s health, and has given me fair warning on a few drives over time, it’s known to be unreliable. Apple has likely not chosen to use it directly for that reason, as well as the fact that as they don’t control it, they can’t fashion it to their own use.

    As Apple doesn’t sell iMacs as user configurable machines, except for RAM upgrades, this isn’t a problem other than for those willing to violate the warrantee they agree to when purchasing the machine. As a seller of goods and services, I would expect OWC to be concerned that this might diminish your business to a very slight degree. But, it’s not really a proper concern, as it does violate that warrantee if people take you up on it.

    I’m not saying that people shouldn’t want to upgrade these drives, only that these machines are not configured for that purpose, and that is understood upon purchase. Therefor Apple is under no obligation to be concerned about it. If they find a way to do something that they feel will make their machines more reliable on a couple of levels, then they should do it.

    If people really want a bigger HDD, they can always add an external drive, likely a safer bet anyway. If they’re willing to send their computer in to OWC for internal, non-warranted surgery, for an external E-SATA port, so be it. But, just keep in mind that an iMac is deliberately designed as a non tinker’s machine.

    • You are incorrect about voiding the warranty. There is no where in their warranty that states you void it by opening the iMac. You only are voided on any damage you cause. If you cause no damage, your warranty is fully intact with the exception of the drive you just installed. Very frustrating when people continue to propagate this false information.

      • Sorry bud but you are obviously clueless. The Apple warranty clearly states to buyers that if they crack open their Macs it is considered tampering and voids their warranty. Perhaps you should learn to read before making such false statements that will ruin someone’s warranty from your bad advice.

        I work as a full time Apple tech and have tuned away many customers expecting free repairs that have broken warranty seals or had clear signs of being inside their Macs.

        Unlesss you are Apple certified stay out of your Macs! Because if you take MacBoy seriously most of you can expect ESD damaged Macs!

        • Well, sorry you say that but I have read the warranty many times. It does NOT say that. It say “any damage due to unauthorized modifications….”. I repeat. ” any damage due to…”. It does not say “if you modify it” Please don’t bother arguing over it. Post where EXACTLY where it says that. I am open to reading what you post but I am certain it is not in the AppleCare agreement.

          I am so tired of this argument with people that just state what other people say. Read the agreement!!!! It is NOT there.

          • For better, or for worse, the thing to remember is that APPLE gets to determine what they consider to be damage unless you live in a state where they have guidelines. If one exists. If you are returning your iMac for a repair, it is probably broken and if the screen is hanging off the front, they are probably not going to be too sympathetic.

            Realistically, why would any sane person crack open their iMac within one year of purchase? If you really needed a bigger drive, you should have got one when you purchased it. Right?

            So, IMHO, the whole warranty thing is moot.

        • And there are no seals broken to replace the drive on a 2010 or 2009 iMac.

        • Straight from AppleCare: “damage … caused by….”

          ii) Damage to the Covered Equipment caused by accident, abuse, neglect, misuse (including faulty installation, repair, or maintenance by anyone other than Apple or an Apple Authorized Service Provider), unauthorized modification, extreme environment (including extreme temperature or humidity), extreme physical or electrical stress or interference, fluctuation or surges of electrical power, lightning, static electricity, fire, acts of God or other external causes;

        • I think you are going to have to provide more documentation that just your word. There are a variety of jurisdictions where this type of restriction would be prohibited by law, and Apple has on multiple occasions stated that opening a Mac for memory upgrades does not void a warranty excepting user-caused damage – see for example their various statements about the MacMini when it was first introduced. In the USA there are a variety of court proceedings that prevent companies from prohibiting third party hardware work by way of warranty voiding language – mostly in the automotive industry but their effect is broader than that.

          Apple’s “Hardware Warranty” as listed on:

          provides no language limiting the coverage for user-opened devices.

  • sounds to me like it’s no big deal?

    Hardmac’s explanation:

    Here is also an explanation of the reasons that pushed Apple to introduce that system in the 2009 iMac. As we sais earlier, the iMac checks very often the temperature of the hard drive. If it was doing so with the SMART system, it would shrink the disk bandwidth and would freeze the disk for a very short time at every check.
    Therefore Apple decided to do it with an Out of Bandwidth system, outside of the data channels of the disks. At first the company used connectors added to most hard drives and used for programming and testing the disk. That solution had one drawback as each manufacturer had its own connector. The 2011 model uses a new system. All the information now goes through pin 11 of the power supply connector, which is normally used to light-up a LED during disk activity. In prodder to change the use of that pin, a specific firmware was needed, which explains the reason that only disks sold by Apple in the iMac don’t have any problem.
    It was quite a radical choice; far from established standards, but in the end, it will not cause any big problem in the replacement of hard drives in these computers.

    • Since you don’t have open access to modify the firmware of hard drives, at least to this point in time, this is definitely a barrier to hard drive replacements in the 2011 iMac. As a side note, I think Hardmac incorrectly characterizes OWC from opinions in the blog and our own commercial interest / impact. That said – as greater understanding is achieved, the fact of the hard drive replacement limitation holds while good reasons for what Apple implemented also come to light.

      I don’t think there is anyone who would disagree with me saying that it would great if the iMac was actually built with more user serviceability in mind. That’s not Apple’s business model and all design considerations are about their own build and servicing requirements with respect to it not being built as a user serviceable system. i honestly can’t hardly fault them on that. It’s how they sell it and it’s our choice to buy. Granted – when the right choice today is Mac OS, you really don’t have much choice in hardware… but it still beats the alternative. :)

      Of further note, when the prior blog was first penned, the writer only knew that anything other than an Apple Rom HD in the hard drive bay wasn’t working right. We were still delving into the exact reasons for this, what was different, etc. Perhaps that blog leaped out a little ahead of the curve…

      But – will maintain, it’s overall good to have had broad discovery and review of the matter. I think it’s going to help save a bunch of people some grief. It should be pretty known now that a SMART monitoring solution to control fan speed needs to be running if you’ve got a non-Apple hard drive in the bay and have intentionally or inadvertently bridged the pin 11 telling the computer to ignore that bay.

      • It’s not much more of a barrier than having to pull the screen off of the iMac to get at the drives in the first place, and it certainly hasn’t dissuaded anyone I know from putting SSDs or other drives in their iMacs in the 2 years that this has been a practice.

        There’s even an article on Engadget about it from last year:

        I wouldn’t claim that OWC is biased because of your business model, but you guys do seem to have a skewed (or, dare I say, sheltered) perspective. Perhaps it’s because you’re coming from a position of providing turn-key or drop-in replacements very similar to drives Apple already offers, but the fact is that people bold enough to set about upgrading iMac hard drives don’t necessarily follow that method (and I would hazard a guess that they represent the majority of such upgraders) — they use other drives that they bought online or locally, which means they need to work around the thermal monitoring. So they deal with it, and this new iMac is not more restrictive in any meaningful way when doing so.

        The problem is that this blog made (and to a lesser degree continues to make) statements that are being taken at face value and interpreted in an overly broad manner, so now you have other organizations and individuals with little understanding of the topic (and for the most part zero interest of ever upgrading an iMac’s hard drive to begin with) ranting about having their options eliminated — which simply has not happened. OWC might have a harder time offering their turnkey solutions, but that is not the same thing.

        I don’t think for a moment that the intent was to create FUD, but that has been the result all the same.

  • According to the Wikipedia page for SATA ( ), there are 15 pins on SATA Power but only 5 different lines: GND, 3.3, 5, 12, and a pin that can be used for spin-up control or for an activity LED. I wonder if Apple drives have modified firmware that pulses that line at a rate based on temperature

  • Something is missing in all of this. There must be some reason why Apple has gone to this.

    Are they trying to kill the aftermarket drive business? That really doesn’t make sense.

    They already make it difficult because of the iMac’s design to replace the drive. I’d bet that more than 98% of iMac owners never replace their internal hard drive, unless it breaks. Then they take it to a repair shop. That’s just the basic iMac market. So, making the operation even more difficult doesn’t seem to be worth the trouble.

    If they are trying to make more margin on disk drives, you’d think they’d apply that across all their product line. But, Mac Book Pros have to be the easiest computer in the world to replace a hard drive in.

    On top of that, they could probably make a bigger killing by making memory hard to replace, since that is the most likely upgrade the average user probably applies. But, Apple doesn’t do that.

    My guess is that either the iMac cooling system is far more fragile than we all understand and they need to keep that under tight control, or that Apple is planning to use some new variation on drive technology that will require special connectors. You could make arguments for either and both.

    Even if Apple was trying to push Thunderbolt, they’d apply the pressure across their product line like the Mac Book Pros where Thunderbolt first showed up.

    If you want to be really adventurous, you could speculate that Apple is trying to keep the iMac very, very quiet, just like they were hunting wabbits. Maybe iMacs are expected to be the first serious platform Apple might push for their next generation of video playback in the home. Those server farms aren’t for faster email responses. For this you’d want silent operation. With laptops, you may not care. Even there, Apple seems to be moving toward the type of “drive” technologies they use in Mac Book Air laptops. An iMac with a large external display via Thunderbolt could be in the future. There’s rumors out there that Apple has hired Thomlinson Holman, so there may be something to this.

    • See the post and reply below….

      I honestly believe this comes down most to simple manufacturing efficiency. Remembering that Apple doesn’t consider the HDD bay a user upgradable, let alone accessible area of the iMac – any design updates aren’t giving any consideration to enduser action with said component area.

      Instead of three different cable sets in their BOM for depending on which MFR’s drive was going in, now it’s one cable for all. If the HD manufacturers had actually agreed on a standard for the original thermal sensor pin implementation, Apple would likely have never done this. Apple’s solution simplifies their warranty replacement service, build, etc. That’s why they did it IMHO.

  • Thanks for the follow-up and detailed testing info, the initial post caused quite a stir over at MacRumors. If it were at all possible, a circuit diagram of the mid 2011 iMac SATA HDD power cable would be very helpful to a lot of readers, I think. (A picture being worth a thousand words and all.) Whenever shorting pins is suggested, especially when there’s 7 pins at one end and 15 at the other, there’s room for confusion. Also when you mention the differences between the HDD PWR connector on the logic board and the ODD and SSD PWR headers (which are not the same on the 21.5 and 27-inch models), you should point out the most glaring difference, which is that it is the only one that supplies 12 V. Also, I am confused by your statement that the ODD and SSD power connections utilize 5 “leads”. The 27″ iMac has two 6-pin slimline SATA power connectors, and the 21.5″ has a 6-pin and a 4-pin header. Does the ODD cable actually have 5 conductors for power? That would strike me as odd.

    It has been written elsewhere that pin 11, the reserved pin of the standard 15 pin SATA power connector, is the one Apple is using for temp data, yet your research seems to indicate that two lines are involved. Is Apple also using pins 1-3 for temp as well, seeing as they’re the only other ones that are generally unused, or are your measurements in regards to GND?

    Also, there are reports of people using SATA power Y adapters when swapping HDDs along with adding an SSD, and they do not have fan issues. I checked an adapter I had lying around and found that pins 10-12 were ganged inside the connector, thus pin 11 was shorted to ground. I’m guessing this is why these setups work.

    Apple apparently wanted an out-of-bandwidth solution for temperature monitoring, and thus avoided using S.M.A.R.T. over the data cable. It would be interesting to see benchmarks of a stock drive with the Apple system versus one using HDD Fan Control.

    • We will continue breaking this down and next week expect another dive into this with the technical details you’re requesting.

      The SMART bit is interesting and will be followed up on. We will test both HDD and SSD and compare sustained full drive read/write fill. I see a note out there that Apple skipped on SMART noting the bandwidth related to how often they want to poll for the temperature. This will be interesting. :)

      I hope those with the ‘working’ drive swap using the Y-Cable are following things as they unfold out there. Of course it works with the grounding of the pin 11. Unfortunately it is working by telling the iMac that the HDD bay is empty… which means no thermal monitoring of the HDD in the bay and no fan revving when needed for actual heat in that bay. regardless of impact an app like HDD fan control or iStat needs to be brought online in those iMacs unless they want to cook their drive.

      Being objective as the pieces all fall in place…Apple as their reasons for not using SMART to monitor temp.Those reasons go back several years and we can do some testing regarding their reasons.

      When Apple used external thermal sensors, most drives didn’t have pin outs that provided that data.

      When drive manufacturers incorporated these pin outs – Apple started using them. Only problem, each drive manufacturer has their own pin type and setup. Apple multi-sources drives and incorporated the unique cable for each mfr by bill of material.

      Apple got clever and found a way for a single cable connector to be utilized and that’s what they did with the 2011 iMacs. No more bom variations for each different drive manufacturer.

      Apple builds systems for a specific advertised purpose. At this point I do not believe this change was done with the intent to make barrier to hd swapping. That said, it does seem likely that this was of no concern and more than an unintended consequence, being objective, it’s probably seen as an unintended benefit (talking from Apple’s point of view).

      We’ve been testing and working with these systems for over a week. There will be correct, confirmed solutions to the best of what there is to work with. If nothing else, the big flag the prior blog raised out to help a few out there prevent unnecessary data loss… They can get a smart fan control utility in place and get those drive bays protected again. :)

    • I think your slightly off on the SMART thing, I think this is because the SMC needs to read the disks temperature sensor and the SMC can’t use the SATA data interface (its not connected to it) but since it controls the power it can read data over the power connector.

      It can also means it can read the temperature sensors and change the fan speed while the Mac is in standby.

  • As I see it, the problem here was two-fold:

    1) the tone and content of the previous blog post demonstrated inadequate objectivity for a company such as OWC
    2) there was a striking lack of awareness about this issue with respect to previous iMacs on the part of the blog post’s author

    The first one is the biggest offense in my mind, but only just barely — I also expected OWC blog posts to reflect a very high level of technical competence and domain knowledge, at least on par with a company such as iFixit, and the beliefs surrounding that assumption were revealed to be in error.

    The fact is, iMacs have used hardware-based sensors for a couple of years now, and anyone attempting to add an OWC SSD to an iMac (such as me, a few months back) has had to deal with that. Just like today’s iMacs, the sensor needs to be disabled or the fan speed needs to be overridden. It is trivial to find discussions of this problem and various solutions online. Since I did it myself when purchasing one of OWC’s drives, I find it really surprising that this is news to anyone writing technical blog posts at OWC.

    As with all such hardware updates and associated utility software since the dawn of the industry, if there was a change in the available fans then any 3rd-party utilities that control them will need an update as well. This also is not news, and there should be no surprise if the solution people were using for the previous iMac needs an update for the new one; if anything, there should be a simple reaching-out to provide assistance to the developer in question.

    As a general comment, the last thing anyone needs is the sort of inflammatory blog post that was authored here. With the headline used, it was virtually guaranteed to be picked up and re-posted by various other sites, resulting in articles primarily attractive to people with no actual interest in the topic at hand, but with an overriding interest in partisan company-bashing — rendering meaningful discussion impossible.

    tl;dr version:
    – OWC should have already known about this issue
    – OWC should not expect Apple to avoid updating hardware just to make things easier for hardware tinkerers
    – OWC should be leading the charge in making sure its customers know how to install and configure OWC products in all recent Apple hardware — not complaining about having to do so, as happened in the previous post

    • The prior blog entry could certainly gone more to technical detail and less about the writer’s opinions on the matter. That being said, we have many different blog contributors and with different styles and intent.

      Michael did comment on the 2009 and 2010 thermal sensor bit, this wasn’t a news flash. With these models, there are plenty of work around options – with the simplest being using a replacement HDD of the same brand as came in your iMac. Nothing to do with firmware, all to do with a lack of standardization about HDD makers in terms of the pin connector for connecting to the thermal sensor out on a SATA Drive. That’s not Apple’s fault at all. Using a different brand drive is an option with a little tweaking… connecting a different end to that sensor cable that will mate up, using an external thermal sensor, or buying the Apple service part with the connection to the desired brand.

      This changes dramatically with the 2011 model. While with 2009 and 2010 you could still have a thermal sensor operating with new drive you installed, feedback there from controlling the hdd bay fan speed. Further – Apple AHT passed without issue as well. That isn’t the case with the 2011 models currently. The 2011 iMacs revv up the fans revv up and AHT fails.

      i posted about one possible solution using the HDD Fan Control which will over ride the Apple control and ramp fan speed based on your settings and the SMART reported temperature data.If you then short the thermal lines, really just closing the circuit, HardMac has now reported this is what Apple is doing on SSD only iMacs which apparently disables/ignores hdd bay thermal data and does so, as we’ve already seen and tested, without affecting the SATA port operation itself. Doing both the hardware mod and installing the fan control gives you an iMac that will pass the AHT test + have the fan ramping up when there is real heat from the hard drive to deal with too.

      For those that aren’t worried about being able to run AHT, the software solution alone may very well suffice. We’re still testing and making sure any given profile will be correct for protecting the drive.

      These iMacs are not an easy upgrade. That said, it’s a fair comment to note we should be more active in promoting the DIY aspects. Our 2010 upgrade program was focused largely on adding an eSATA port. Even with Thunderbolt, I think that is still of value for plenty of good reasons – but – with 6Gbp/s SATA 3.0 inside and SSD options maturing, drive upgrades now appeal to a much larger audience.

      With warnings galore, once we’re comfortable with the ultimate solution – you will see us offer drive upgrade kits for these iMacs and likely older models as well… certainly for the SSD bay regardless of what happens with this HDD thermal reporting debacle.

      Mike’s blog was directed at the DIY side of things, but with all the upgrade program mentions. We have supported users for DIY adding their own drives to 2010 and prior iMacs, but not visibly enough which can make a further perceived contradiction in the article. The article is effectively an opinion piece on some specific technical changes in the new 2011. In hindsight, had this article been in response to a report on these observed points, would have been perceived differently. We’re immersed in this stuff and, if nothing else, underplayed the news of the actual technical bit itself and… how much interest and pickup there would be on this matter. Once all solution options are fully played out, we already planned to cover that (and will) in a future blog.

      Thanks for the commentary and feedback.

      • Thanks, Larry.

        Regarding this:

        “This changes dramatically with the 2011 model.”

        For anyone doing an SSD upgrade — the biggest performance upgrade you can make to an iMac, and a use-case directly cited in the previous blog post, and — It just doesn’t.

        “i posted about one possible solution using the HDD Fan Control which will over ride the Apple control and ramp fan speed based on your settings and the SMART reported temperature data.If you then short the thermal lines, really just closing the circuit, HardMac has now reported this is what Apple is doing on SSD only iMacs which apparently disables/ignores hdd bay thermal data and does so, as we’ve already seen and tested, without affecting the SATA port operation itself. Doing both the hardware mod and installing the fan control gives you an iMac that will pass the AHT test + have the fan ramping up when there is real heat from the hard drive to deal with too.”

        For people buying OWC’s terrific Sandforce-based SSDs, that’s what they’ve had to do all along: short the sensors (required to prevent fan run-up) and use a 3rd party utility to monitor S.M.A.R.T & control fan speed. There is nothing new here other than a change in which wires you short.

        Further, given the large performance increase the 6Gb SATA provides for the newest drives (as Anandtech’s in -depth reviews demonstrate), for anyone making a purchase right now the new iMac is a much better candidate for SSD upgrades than the previous one — an inescapable conclusion for any enthusiast, and one that flatly contradicts the previous blog post.

    • I need to back up OWC and critique Michael:

      OWC is a business that is successful off of Apple
      OWC may be biased but it is OWC’s blog and opinion.
      OWC has credibility and provides “outstanding” support to customers and others.
      OWC makes money selling replacement and add ons for mac users.

      Now with that stated, comparing OWC to iFixit is inciting argument on poor information. iFixit clearly is a traffic-generating web whore with “me first” images of mac product takedowns. The day will come when they will cease (or sell) because of a lawsuit indicative of not taking ESD precautions in their videos and a consumer(s) loses valuable $. ifixit merely wants attention (see revenue clicks/traffic). iFixit appears not to provide anything more than unboxing and some trivial information about chip serials and manufacturers. Remember the “inflammatory” posts iFixit started with the “pentalobic” screws on the MBA? You should, Michael, as it is no different than Apple’s “proprietary ROM/firmware” at work here.

      Michael’s post has contributed nothing.

      Now a finger at anyone that feels upset that a manufacturer changes something that hurts the very business exploiting its profit. You have a choice not to buy it. And if you get LOUD enough, change will come.

      PS. Where are all the Thunderbolt accessories!!! And where are MBA SSD adaptors? Doesn’t Apple care (pun) that we will lose data?

      • Everyone is absolutely entitled to their views. Always challenges to overcome seeking a solution that, for reasons commercial or functional, the manufacturer seeks to put barriers towards. At the end of the day it’s up to the customer what computer to purchase. I think it’s just frustrating that some of these barriers are there to begin with.

        MBA SSD external support is coming. Tricky connector. But it’s coming…

        Thunderbolt is really in its infancy – next year will be the boom for that imho. this year’s products are going to be pretty limited. There are reasons you can’t even get a thunderbolt cable yet today, let alone thunderbolt device. Apple/Intel picked a couple to start things off there and they will have the early plays (not their fault, not implying at all, that these early players have any fault or anything to do with there not being thunderbolt products yet). Lots of fun stuff on the horizon.

        • Hi,
          i was thinking of replacing HDD in 2011 21.5″ and using your cable with heat sensor. If I also want to put a SSD under optical drive or smilar do I need a second heatsensor kit? thNKS

            • Hi there.
              I know this is an old thread but I’m in a fix with my 2011 27″ iMac. I bought the machine second-hand with a fusion set-up (purchased originally like this or upgraded I do not know), 1 To hard drive, 128Go SSD & 32 Go memory. The SSD began reporting errors so I removed the Fusion setting in the Terminal and used the machine for a while with just the HD and no problems. I have been trying to replace the old SSD with a Crucial 500 Go SSD, using the existing SATA cable. Everything works fine for a while but then the SSD corrupts – eventually impossible to repair it. I have had a replacement from Crucial and the same thing has happened. I’m awaiting another replacement (3rd attempt…) and hope to avoid the same thing again. In your thread you state that the thermal issue is not a problem if just adding an SSD behind the optical drive. Any thoughts or help would be appreciated! Thanks.

      • As you appropriately note, this is opinion…everyone is entitled to such. And this reply is more addressed to many than you ehski.

        Regardless of affiliation with OWC…the blog team and to wider scope of OWC employees are Apple product users and consumers. And as such, when we feel that our choices have been diminished and or reduced, well, we’re not going to go quietly into the night.

        I’m not defending OWC Michael…but as I oversee many of the posts before they go up…this was a shared outrage by the entire OWC blog team…who often disagree on Apple and industry related topics during our OWC Radio podcast.

        In the end, I feel the post was warranted just merely by the number of those feeling like we do about diminished choice and those that have a different take on the subject.

        At the very least, sure brought a lot of interest to the iMacs and a potential future of more proprietary engineering by Apple. That in itself may wake up those planning such and remember that you need to listen to customers first (marketing) than dictating what they must buy (sales).

        Thanks for the input!

    • Hardware tinkerers? You must be kidding if you think of changing hard drives as “tinkering”. This is nothing like changing various resistors to affect line voltage or any of the various mods/tweaks that have been done in the past.

  • Hey guys: Any comment on the following Macrumors thread:

    Specifically, that an Apple Rep told a potential customer these new drives (with new standards) would be available to third party vendors (like OWC) by Summer. I’d love to see what you guys here from Apple as well, if you can get a response.

    • Comparing the two Apple Factory WD1001FALS drives today revealed no apparent hardware difference on either side of the drive PCB. The only confirmed difference is the one from the 2010 Mac Pro didn’t engage with Apple’s thermal reporting and resulted in AHT failing on that note – while, of course, the unit from the iMac was fine.

      None of the three drives we pulled from the iMacs are exactly ‘new’ drive models. In fact, they are all older SATA 2.0 3Gbp/s models already replaced with newer versions. What allows them to work appears to be in the firmware and as those extra pins are on the non-Apple hdd drive side power port, I’d expect that the functional capability isn’t new either. Likely the same function provided via the separate pin outs, but a better solution for integrators when can do it with a single, standard, SATA connector to the HDD side vs. having to maintain different cable sets for the different brand HDDs to use the pin outs that are not consistent brand to brand.

      We did observe different operating voltages between the different brand drives off those lines when in operation (talking about the 2011 and the new thermal lines integrated into the power connector).
      I would speculate that Apple does have special firmware in place – it recognizes the drives with trusted parameters – and allows the thermal monitoring to then read the feedback based on the voltage feedback expected from brand x hard drive.

      if this is the case – Apple could potentially do an update down the road which would not require Apple firmware be present on the drive for this feature to be work, AHT to pass, and the fans to run as intended with a non-Apple firmware hdd.

      We will see. But there is, and I am repeating, nothing to suggest that these hard drives have anything new or different physically related to the thermal reporting point of connection change. There are plenty of other practical issues that would preclude this as well. I am comfortable saying that the difference is, if nothing else, in the drive firmware. If it was a custom hardware drive model, I don’t believe the drives would have the same part numbers they do either.

    • “new standards” – that’s the most hilarious stretch of the definition of standard I’ve ever heard…