As you may recall, Apple changed the hard drive upgrading game with the  2011 iMac.

Up until 2009, changing a drive was easy once you could get to it. A few screws here, a connector there and voila – you were good to go. And OWC had you covered for all your iMac DIY hard drive upgrades.

With the late 2009 iMacs, Apple introduced a different connector for each brand drive, but as long as you stayed within the same hard drive brand, then it was the same, once you got to it – it was easy-peasy to make the old switch-a-roo. And OWC had you covered for your iMac DIY hard drive upgrades.

Then came the 2010 iMacs and the ‘same for same’ caveat still applied, but the 27″ iMac model introduced an additional SATA drive connection on the motherboard and the OWC Turnkey Upgrade program was born. Send us your 27″ iMac and we’d add up to 3 SSDs or even an eSATA port. It was a little more difficult, so we started with a do-it-for-you service, then made it available as a DIY kit. And OWC had you covered for all your iMac  DIY hard drive upgrades.

Lo and behold, the 2011 iMac changed the game again, no longer could you swap out the drive without failing the Apple Hardware Test (AHT) and sending the fans into a tizzy. Soon after, we expanded the iMac Turnkey Program with our Do-it-for-you service on these machines as well. And, now, we’re happy to announce that we’ve crafted that solution into an elegant little DIY Kit. So, once again, OWC has you covered for all your iMac DIY hard drive upgrades.

(OK, ok – we’re still working on the late 2012 iMac drive options, and – please – give us a little more time there. Apple changed it up again going to the new form factor iMac with a blade-style SSD.)

So how did we do it? 

Well first, a little background on what the issue is exactly, and what is the proper way to solve it…

Apple introduced a firmware element to hard drives that are factory-installed which allows the drive’s internal temperature monitoring system to communicate with the System Management Controller (SMC) which controls the power functions, battery, the sudden motion sensor, the fans, and other functions. When the SMC doesn’t receive temperature data it expects,  it goes into failsafe mode directing the fans to rev to full speed and further reporting drive sensor failure via Apple Hardware Test.

When installing a hard drive that lacks the special Apple firmware, the SMC goes into failsafe mode since it is no longer receiving data on what the drive temperature is. The fans then rev to max on the basis that a drive is in the bay and it wants to ensure protection of the drive regardless of load on the drive and heat level from ongoing loads.

There have been several forums and blogs that offered workarounds to this situation, but these hacks weren’t optimal:

Some sites suggested shorting pins in the power cable or drawing power from another drive bay so the drive no longer would be expected to report temperature information at all. But allowing the drive to get too hot can easily cook a drive.

Others suggested to use 3rd party software to to manually control fan speed.  This software is not free nor an ideal solution as you run the risk of overheating if mis-configured or disabled by accident, software update, or OS re-installtion.

Simply put, lack of active heat monitoring could lead to a drive failure.

What is the solution for the 2011 iMac, then?

The OWC HDD kit provides a cable with a digital thermal sensor module that is able to ‘talk the same talk’ with the SMC. By replacing the stock Apple cable, the SMC is no longer relying on the Apple firmware for temperature data.

Use of this kit allows the installation of any standard 3.5″ Serial ATA hard drive with capacities now up to 4.0TB. With the included custom cable, the HDD bay has proper thermal monitoring communication, the iMac will pass AHT testing, and the HDD bay will be properly cooled per Apple settings just like the original factory drive. In short – an optimal solution for your 2011 iMac hard drive upgrades.

While you’re in there – you’ve got a great opportunity to consider upgrading or adding an SSD for a super performance boost. The OWC SSD kits make that easy too. And if you purchase one of our full kits, you can buy just the support kit (without the tools) for the 2nd upgrade portion.

Finally, don’t forget memory – most systems shipped with only 4GB of memory and with today’s modern Operating Systems – there are benefits for having up to the 32GB maximum the iMac 2011 models support. With 4 slots for memory and only two typically occupied from the factory – it’s easy and provides a night and day performance boost for many applications when you add even just another 4GB, 8GB, or 16GB to that existing memory.

We even walk you through, step-by-step on how to perform each of the above the upgrades in our Installation videos for the 2011 iMac models.

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