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How to Reset NVRAM, PRAM, SMC on Your Mac

macbook_pro_2012_2013Macs are incredibly reliable computers. But occasionally when using one, you’ll come across an issue. With so many variables, troubleshooting your Mac or macOS (or OS X) on the rare occasions that it does act strangely can be an intimidating.

Fortunately, and OWC have an expert Customer Support team in place to help 24/7. But sometimes, you’re not able to reach out for help, and a simple restart or even a reinstall won’t do the trick. Maybe your volume control is grayed out, your battery charge indicator isn’t accurate, you’re having Bluetooth problems or your computer won’t turn on at all…

What should you do in these cases when you can’t quite figure out the issue? A relatively quick fix for your problem might be to reset the NVRAM (or PRAM) on your Mac, or maybe a reset of the SMC is in order to get it running correctly. But before we show you how to take these steps, first let us explain exactly what exactly these acronyms mean.

What is PRAM, NVRAM?
PRAM stands for “parameter random-access memory” which is essentially a small amount of memory that stores certain settings in a location that OS X can access quickly – things such as mouse settings, speaker volume, virtual memory, screen resolution and other core data needed before OS X loads.

Newer Macs, however, no longer use PRAM and instead utilize NVRAM or “non-volatile random-access memory”. NVRAM serves essentially the same purpose as PRAM, storing information such as speaker volume, startup disk selection and recent kernel panic information among other things.

How to reset NVRAM (or PRAM)
If your Mac is not booting correctly or one of the functions listed in the previous section is acting strangely, you can perform a simple reset of your Mac’s NVRAM or PRAM. Resetting your Mac’s NVRAM or PRAM will reset the data stored to its default setting. (Note: As always, we strongly recommend having a complete backup of your important data before troubleshooting your Mac.)

The process for resetting PRAM and NVRAM is exactly the same. Simply follow these steps:

1) Turn your Mac off.
2) Turn on your Mac and when you hear the startup chime, immediately press and hold the Command-Option-P-R keys. (Note: You may need a wired keyboard for the reset).
3) Hold the keys until the Mac restarts and you hear the startup chime for a second time and then let go of the keys.

After resetting NVRAM or PRAM you may need to reconfigure some of your Mac’s settings. If you are still having issues with your Mac, you might want to consider resetting its SMC.

What is SMC?
On Intel-based Macs, SMC stands for System Management Controller. The SMC chip controls your Mac’s sleep function, power, various lights and indicators, fan speed, and keyboard backlights among other things. So if your Mac’s fan is out of whack, indicator lights are misbehaving, it won’t respond properly when closing the lid, or the Mac won’t turn on at all, you might want to reset the SMC. (Note: Again, be sure to have a complete backup of your important data before resetting the SMC)

macbook-air-13-inch-battery-installedHow to reset SMC in a MacBook with a removable battery
1) Shut down the Mac and disconnect the power adapter.
2) Remove the battery.
3) Press and hold the power button for 5 seconds.
4) Reconnect the battery and power adapter and press the power button to turn on the Mac.

Note: The LED on your power adapters might change states or temporarily turn off when you reset the SMC.

How to reset SMC in a MacBook with a non-removable battery
1) Shut down the Mac.
2) Connect your power adapter to your Mac and to a power source.
3) With the Mac powered off, press Shift-Control-Option and press the power button at the same time.
4) Release all keys and turn on your Mac.

p_featimac27How to reset SMC in iMac, Mac Pro, Mac mini
1) Shut the Mac down and unplug the power cord.
2) Wait 15 seconds with the Mac unplugged.
3) Plug the power cord in and wait 5 seconds.
4) Turn on the Mac.

This Apple Support page has a list of steps you can take before resetting the SMC that may be useful as well as a longer list of issues that might be resolved by an SMC reset.

The recommendations in this article may or may not solve your Mac’s issues, but they are a valuable step when troubleshooting. If you have further issues, our Customer Support team is available to assist. Be sure to check out the Rocket Yard’s Tech Tips section for more great Mac tricks!

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  • lots of thanks to you for caring to help and sharing this useful document

  • Ok- Startup Chime. My new iMac has NO start up chime. How do you zap the PRAM in that situation?
    No article I read ever talks about this.

    • Due to the new “security chip”, new Macs don’t have a startup chime. Had to call apple about this when I got my new Mac mini.

  • Even with 10.13.6 (latest update) installed, the steps you state will fix the “Sleep Wake” problem do not work. Apple acknowledges this is currently being looked at, but for now, there is no fix. They say just keep installing updates until it gets fixed. Given how long this has been going on that’s not very satisfying…

  • iMac shows a WHITE screen at the starting.
    Already Erased the HD once and reinstalled the program. Already, changed the HD for an SSD, installed the program, already reset the PRAM, already used the SAFE MODE already re-installed the system.
    When I use an external HD using the option Key at the start up, everything works just fine. Not Blank screen whatsoever.

    What should be the issue

  • I recently ordered a 16 GB RAM upgrade for my MacBook 7,1 (mid-2010) which did not work. OWC promptly replaced it, and even after two hours with Tech Support (Cynthia), still couldn’t get it to work. She had me check my SMC version, which was up-to-date, but still no go (she’s great, BTW). I’m going to order an SSD first, and in the near future will re-purchase the RAM upgrade.
    I am a huge fan of OWC, and I often save many of your tech blogs as PDFs for future reference.

  • Can one reset the SMC in a PowerPC (pre-Intel). I seem to be having a fan issue. I did try resetting the PRAM and although I was *thrilled* to get my start up chime back, it didn’t solve my problem, which is that when I put my computer to sleep, the fan seems to wake it up and starts going really fast and even holding in the start key won’t turn it off, and I have to cut the power.

  • Your 4-step procedure for a non-removable-battery Mac does not match Apples’s 6-step procedure shown on the Apple support page you linked to, particularly about being plugged in to power and holding down keys. I’m concerned that it might make a difference. Do you need to adjust your procedure?

  • I see this info on various sites but usually not altogether. One question that I have on the waiting times. Would you say that you should wait at least 15 seconds or does it not work if you wait 30 seconds?

  • Sharp, concise, and informative. A lot of Mac owners and users would be well-advised to check this info out and increase their knowledge base. Goes without saying that Macville is a desirable place to live and work.

  • this might come off as a silly question, but does resetting SMC & PRAM itself, get rid of all your files, or just put them in danger of being lost?

  • Would be great to have a sticker with this information — and a shout out to OWC — to put on your machine.