You can make a difference in the Apple Support Community!

When you sign up with your Apple Account, you can provide valuable feedback to other community members by upvoting helpful replies and User Tips.

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

add memory to 5k 27" 2017 iMac

I want to extend the memory of my 5k 27" 2017 iMac. It now has 2 4GB memory modules, so another to modules can be added. Doe these extra modules also need to be 4GB, or can I also add 2 16GB modules?

iMac 27″ 5K, macOS 11.2

Posted on Mar 3, 2021 4:53 AM

Reply
Question marked as Top-ranking reply

Posted on Mar 3, 2021 5:02 AM

It's recommended not to mix capacities and speeds

Install memory in an iMac - Apple Support


For optimal memory performance, DIMMs should be the same capacity, speed, and vendor. Use Small Outline Dual Inline Memory Modules (SO-DIMM) that meet all of these criteria:

  • PC4-21333
  • Unbuffered
  • Nonparity
  • 260-pin
  • 2666MHz DDR4 SDRAM

If you have mixed capacity DIMMs, see the 

install memory section for installation recommendations.



My recommendation would be to just use the 2 16 GB modules. as an extra 8 GB rarely will make much difference.


But you can try and see, as long as you follow the guidelines it should still work.


You can always just remove the 2 4GB modules if it misbehaves.


Good luck!


3 replies
Question marked as Top-ranking reply

Mar 3, 2021 5:02 AM in response to Mars234

It's recommended not to mix capacities and speeds

Install memory in an iMac - Apple Support


For optimal memory performance, DIMMs should be the same capacity, speed, and vendor. Use Small Outline Dual Inline Memory Modules (SO-DIMM) that meet all of these criteria:

  • PC4-21333
  • Unbuffered
  • Nonparity
  • 260-pin
  • 2666MHz DDR4 SDRAM

If you have mixed capacity DIMMs, see the 

install memory section for installation recommendations.



My recommendation would be to just use the 2 16 GB modules. as an extra 8 GB rarely will make much difference.


But you can try and see, as long as you follow the guidelines it should still work.


You can always just remove the 2 4GB modules if it misbehaves.


Good luck!


add memory to 5k 27" 2017 iMac

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.