Hello there.
I want to replace my iMac (21.5 inch, Late 2015) HDD with a 1TB SSD.
Will any SSD work?
Thanks in advance for your advice.
iMac 21.5″, macOS 12.7
Not just any. If you really want to do this, I recommend this source: https://eshop.macsales.com/
Personally, I wouldn't put any money into a 10 year old Mac.
Opening up and resealing one of those 21.5” iMacs is going to be rather involved. If the hard drive is nut actually failing and throwing errors, you might want to consider an external SSD in a USB enclosure, instead.
The new macOS updates will drop support for Intel iMacs soon, so 2019 or earlier will be out of luck on being officially supported beyond that.
Your 2015 iMac probably has SATA III which tops out around 6GBs, even for a fast SSD, you won't get any faster than the interface on the motherboard. (not sure what the speed of the PCIe interface is, probably similar, if you had a Fusion drive the SSD would be on the PCIe and the RPM drive would be on the SATA III.)
Your iMac likely has external USB 3 ports, which top out around 5GBs, not too shabby.
You might consider adding a large and fast external hard drive, install the OS and everything on that and boot from it. You might not notice much difference in speed compared to the internal on those 2015 era iMacs anyway. Then, migrating to a newer machine later may be easier if you can connect the USB 3 drive to a new computer in your future. The external drive is a pathway to get more storage space now, and take it with you later.
For example: https://eshop.macsales.com/item/OWC/MSU3SSDT1.0/
+1 total waste of money to invest in a 10 (almost 11) year old obsolete machine.
FYI, that 21.5” Late 2015 iMac cannot update past Monterey.
SSD replacement iMac 2015
