My late 2009 iMac's internal drive had started to develop issues, and the system had become very slow to boot and start applications. Rather than wait for the disk errors to increase, and the drive to fail at an inconvenient moment, I wanted to be proactive and replace the HD with another 2TB internal drive. I was aware of the generic HD compatibility issues with this model of iMac, and had found my way to OWC (Macsales) based on some online recommendations regarding the inline temperature sensor solution OWC had available to address that issue.... I really didn't want to have to rely on software to run in order to stop the fans running unnecessarily fast/loud.
The kit arrived quickly, and I made sure to review the OWC installation video a number of times to make sure I was completely familiar with the process. After backing up my important data to an external HD - to supplement the time machine backup I also have... I'd rather have more than one recovery source for treasured data), the disassembly process went well. Having a good adjustable desk lamp (or someone there with a flashlight shining on the connectors as you work on each) is very helpful. The only cable that seemed a little risky to me was the display connector, which has pretty fragile side levers in my experience. Still, all was well getting the various connectors/cables off, and the 27" display unit out.
The rest of the process was very easy, in my experience. While I was in there I had also opted to replace the optical drive (my original one was having problems reading CD's, and while dust on the lens was a likely culprit (6 years of constant use could do that), I preferred to take the proactive route in the hope of avoiding having to crack the iMac open again any time soon...). Both HD and Optical Drive installs were simple to do, following the instructional videos on the OWC site. I also used Google to find a couple of other how-to videos, to get different angles on the same process... although that wasn't really needed.
The kit I received also included a small gold flexible cable/connector that I wasn't expecting to find in there, and wasn't sure what purpose it had... none in my case. This turned out to be an SSD connector or some sort, but not a part that was needed for my internal HD swap. Just put that to one side, and follow the video instructions.
One thing I did while taking it all apart was to take pictures of each connector/cable before disconnecting them. Then, I had a close-up reference to check when re-connecting, to be totally sure each was plugged in the right way round, etc. Not needed in the end, but nice to have if you prefer to triple check something before powering up.
The system powered up without issue, and I was able to successfully install a fresh copy of El Capitan from a USB drive installer I'd created. The only unnerving part of that was an install count-down that stuck at "1 second remaining" for 5-10 minutes (seemed like an eternity), but that install step finally did whatever it was doing under the hood and the system rebooted on the new HD/OS perfectly. Apparently this "hang" / delay at the end of the install process is a well known issue.
I opted to install a Toshiba 2TB Hybrid HD (8GB of SSD storage cache within the 2TB HD, where frequently accessed blocks/files are stored for faster access). All I can say is that the system now boots -significantly- faster with this new HD, and applications are similarly faster to load. How much of this difference is due to the new Hybrid drive, fresh/clean OS install, or the very marginal state of the HD it replaced, is tough to say.
Very happy with the value and quality of this kit, and the instructional install video provided. The alternative is dropping $2-3k on a replacement iMac, so the cost of this kit and a new HD (<$150 all-in) seemed worth trying. It feels like a new Mac now, and I'm hoping to get a year or two more use for this relatively small investment.
