The HDD on my Late 2012 27” iMac has died. Is it replaceable?

At present, I switch it on (soundless) and get the white screen which loads up one third and then freezes. I tried Disk utilities which told me my HDD was inaccessible and un-repairable.

If I fit a replacement HDD, will I be able to restart, revive, reuse my computer?

2 Answers 2



The HDD in my fusion drive in my personal 2012 iMac died. I decided to open the iMac (requires removal of the screen) and replace the internal spinning drive with a Samsung 850 SSD to improve performance.

The job will take about 90 to 120 mins total. Most of the time will be spent separating the glue between the aluminum housing and the display glass. Once you separate it, you can easily remove the glass and gain access to the drives extremely easily.

iFixit.com has excellent instructions on how to do this. A couple of items you will need are:

iFixit will recommend that you use one of those special tools to cut the adhesive. I used a super sharp Exacto knife and wrapped some blue tape around the blade so that only a 1/2" of the blade edge exposed. I cut all around the three sides then used a plastic putty knife to pry it loose.

It is much, much easier than it sounds. Read the iFixit guide 3 times carefully before starting. It will make it go much easier.

One thing to note is that in my particular machine, what I thought was an hybrid (Fusion) Drive was actually two drives put together (a 128GB SSD and a 1TB HDD) using CoreStorage (a DIY Fusion Drive). I added the Samsung SSD to the one already there, combined them into one volume and I have a 1.12 TB HDD

If you can boot your Mac, issue the command diskutil list and if you get anything that appears to be 3 drives in total, you have a DIY Fusion drive.

If you can't boot, you will need to take a look at the SSD connector on the logic board (it's by the fan).


I have a 2010 iMac and the drive was failing. I purchased a 1 TB external SSD and connected it to my iMac. I set that drive as my startup disk and restarted. My computer worked fine using this setup and no real effort was required. It was connected to my iMac using the USB cable included. I don't get all the speed improvements you normally get with an SSD due to the USB-A connection offered by my iMac. Maybe your 2012 has a faster USB connection. This is another option to the excellent answer by @Allen.

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