2011 2” iMac HDD Replacement


Hi all,

I have a 2011 iMac that needs a new HDD
I know that previously you need a thermal sensor harness do do this, is that still the case or has someone come up with an alternate solution?

Cheers & happy new year


I think you may be better off with a SSD and software to control fan.

That was what I had installed in my 21.5" iMac and it made it so much faster than a mechanical HDD.

If unable to install yourself I am certain you will find a local that would do a great job.


I did this a few years ago. The OWC video is very helpful, they also have a kit to fix the sensor problem. You can get from https://www.macfixit.com.au/catalogsearch/result/?q=mid+2011+imac+27 in Australia.
Sometimes cheaper from OWC https://www.macsales.com who will ship to Australia, you can do the sums.
Good luck!


Firstly let me start by reminding you or letting you know in case you didn’t the 2011 and 2010 iMac’s Supports up to 3 hard drives internally.

A 3.5, The main drive and yes this model does require a thermal sensor (preferred) but you could use fan control software. The software can be more of a problem and requires you to always find and maintain it where the sensor can be set and forget.

Second drive is a 2.5, and was intended for an SSD ad on sold separately where Apple would install you a second SSD for the operating system. This was way before Fusion Drive came along.

In less you purchased this upgrade when you purchased your machine the cables are missing. However OWC sells the kit including the cables for this however you will need to remove the computers logic board to do this upgrade.

If you’re running one of the later versions of the operating system you can use the slot to DIY a Fusion Drive.

When doing these types of DIY Fusion Drives I recommend a 128 GB SSD when you’re using a spinning hard drive with the capacity between 1 to 3 TB. And 256 GB SSD for anything bigger your 4 to 10 TB drives.

And finally you can replace the optical drive with a 2.5 drive. This is relatively easy to do but does require an additional purchase of an adapter. This slot could also be used for a DIY Fusion Drive.

All the slots can be used for hard drives or SSDs when purchased in the relevant form factor and 3.5 to 2.5 drive adapters can be purchased relatively cheaply.