Suggested SSD drive for 2015 iMac upgrade?

I may be getting a used iMac (Retina 5K, 27-inch, Late 2015). It only has a 500GB drive in it and I am already using 1.4TB on my current 2013 iMac. I had the internal drive replaced with a 2TB SSD a while ago. So I will need a new hard drive.

Unfortunately we no longer have any place to get Apple hardware upgraded or fixed on this side of the mountains and I’m not going to drive for 10 hours (5 each way) just to get a hard drive replaced. I’m thinking of using a 4TB external drive instead.



What is your higher need with this seven year old machine, faster boot + app loading times independent of storage space for files or greater storage space independent of speed to boot / load apps?

The former speaks to replacing the internal drive with an SSD (and perhaps increasing / upgrading the RAM). The latter speaks to adding an external drive as well as perhaps some diligent, manual swapping out of “active” project folders to/from external and internal drives as needed.


Ability to run at least Monterey. My current machine cannot go higher than Catalina.

I need/use lots of storage space and the IDE’s I use (Pycharm and Android Studio) do not perform particularly well when their files etc are on a slow drive. I typically boot all the apps I use regularly at once in the morning and they stay up until evening when I shut apps down so my overnight backup can run cleanly. So reboot times for apps not a big deal. OTOH system reboot times are important because when I need to I am usually in a rush and need the machine up and running quickly.

Ram on this machine is 24GB, My current iMac (21.5-inch, Late 2013) has 16GB. Current iMac has a 3.1 GHz Quad-Core Intel Core i7

Newer machine is actually a step down in power with a 3.2GHz quad‑core Intel Core i5. I’m not sure if I’ll notice the difference but I might.


Can you swap out the 2TB SSD with the 500 GB HD? IOW, downgrade the drive on the 2013 iMac to the drive on the 2015 iMac and upgrade the drive in the 2015 iMac to the drive from the 2013 iMac? Can you do the hardware swap physically? All else being possible, will it matter that you loose the storage on the 2013 iMac (e.g. because it will be “retired”).

If so, what about this approach …

Get a 2TB external HD. Transfer all document-related + preference-related files off the 2TB SSD and off the 500GB HD onto the external drive. Swap the drives and do a (clean) erase + install on the OS. Put back the requisite files from the external drive.

Put aside the 2TB external as your snapshot archive drive marking this point in time.

Get another external drive for whatever you are needing to expand and/or to backup.

Time consuming … yes. The advantage is that your “new” 2015 iMac will not be bottle-necked in storage by its current 500GB drive and can save you from the slower USB transfer rates to an external hard drive to try to make up for that bottle-neck.


I replaced recently the FusionDrive of my 2017 5K 27’’ with this SSD

and this enclosing

and it works very well for me. I did not need to open the Mac, and it has also the big advantage, that I could take my drive with me, if I swap the next time, or have some other reason for this.
I have an 2nd external Drive for the Data I don’t need on the faster Drive.

I would in general think about the future when I buy a drive like that, and spend the money rather on something, I can use beyond the current Mac on my Desk.

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Not really. My old machine is going on to my husband who will be running Linux on it and also doing major SW development so also needs the large hard drive. He’s upgrading his system from an even more ancient MacBook

We have a family systems swap going on

The idea of a big external drive as the main drive has it’s appeal. I’m looking into it now.

I have a couple of Sabrent Rocket TB3 2TiB drives that are now two years old and have had no problems with them, and performance is good.

The 2015 iMac looks like it has TB2, and USB 3.0, so something like this should give you the max speed of USB 3.0: