Single or Dual Rank for iMac

[posiej]

According to the research I have done one can't combine single and dual rank ram. I am in the process of purchasing an iMac 27 inch late 2017 that comes with 8G Ram. I will be purchasing more RAM and would like to have it ready to install when I get my new machine. I have found what I want and it comes in either single or double rank. Does anyone know what rank the installed RAM for my new iMac is? Thanks!

 

[casperes1996]

Well, you can mix and match rank across different channels, just preferably not on the same channel.

But pretty sure it's dual rank

 

[gian8989]

if you buy the iMac with 8GB ram it will come this way: 4 - / - 4 - / .
So if you want to add 16GB ram the best way is with 2x8GB : 4 - 8 - 4 - 8.
This way if it happen that the apple ram has problem with the one you buy you can remove apple ram and still have 16GB in dual channel.

 

[posiej]

if you buy the iMac with 8GB ram it will come this way: 4 - / - 4 - / .
So if you want to add 16GB ram the best way is with 2x8GB : 4 - 8 - 4 - 8.
This way if it happen that the apple ram has problem with the one you buy you can remove apple ram and still have 16GB in dual channel.

I took your advice and purchased 2 x 8 and if I need to remove the 2 x 4 I will and when my budget allows I will purchase the other 2 x 8. Thanks!