Upgrade from SATA to SSD/Flash Hard Drive for Late 2015 21.5" iMac

[jjkyle4]

Upgrade Late 2015 21.5" iMac from SATA to SSD/Flash Drive.

Back up system with Time Capsule or some other form of backup. I recommend the following equipment and how to video.

This flash hard drive:
Crucial MX500 1TB 3D NAND SATA 2.5 Inch Internal SSD - CT1000MX500SSD1(Z) (amz0n for $135)

With this kit:
Replacement LCD Panel Adhesive Tape Strip Sticker + Opening Wheel Tool Kit for iMac 21.5'' 2012 2013 2015 2017 A1418 (amaz0n $10) (There are also other kits that have additional tools if you prefer but aren't necessary)

With this How to video:
Search on OWC for
iMac 21.5-Inch (Late 2012)
Hard Drive Install
Step-by-step video of how to install a Hard Drive in the Apple iMac 21.5-Inch Late 2012-2015.

It's better to format the new SSD with AFMS before installing it but it's not required. I didn't do that. There are USB cartridge devices that allow one to insert and format the new drive externally before installing it.

 

[iMacGuru]

I also have a late 2015 21.5" iMac. I'm running Mojave but I keep getting CPU stalls and bouncing beach balls. Would upgrading the HDD to internal SATA SSD increase the performance sufficiently to reduce the problems to tolerable levels?

 

[mikehalloran]

I also have a late 2015 21.5" iMac. I'm running Mojave but I keep getting CPU stalls and bouncing beach balls. Would upgrading the HDD to internal SATA SSD increase the performance sufficiently to reduce the problems to tolerable levels?

Night and day.

Is yours HDD only or a fusion drive? Doesn't matter on the 27" but can make a difference on the 21.5"

 

[iMacGuru]

Mine is a fusion drive. I attached a 256GB SSD and use it as the boot drive. Mojave still doesn't behave well. I am now running High Sierra on the external SSD. All works great!

 

[mikehalloran]

Mine is a fusion drive. I attached a 256GB SSD and use it as the boot drive. Mojave still doesn't behave well. I am now running High Sierra on the external SSD. All works great!

Decouple the fusion drive and Mojave will run great. High Sierra does not support APFS and is not recommended on fusion drives.