2019 iMac 27 inch RAM addition

drew.bowser

macrumors regular
Original poster
Sep 23, 2008
107
8
Missouri
Quick question, couldn't find the answer in a quick search. Does the 27inch 2019 iMac need RAM in pairs? Im thinking about adding 16gb, but couldn't find if there is a performance decrease by adding 1 16gb stick or if it is even OK to only add one chip. Thoughts?
 

Hexley

macrumors 65816
Jun 10, 2009
1,006
99
IIRC it's dual channel so you will get better performance if matching RAM SODIMMs are installed.

I'd give it a try and buy a 2nd 16GB stick you arent happy with the performance.
 

JacobHarvey

macrumors member
Apr 2, 2019
93
65
Somewhere
Use two sticks with matching specifications (preferably buy a kit with two of the exact same RAM sticks) and make sure you install them in the correct slots so they are in dual channel configuration.

Having two sticks installed in dual channel configuration will give better performance than one larger stick (of the same total capacity) running in single channel.

If you are just adding to the two sticks already in the iMac it is probably still better to go with two smaller sticks than one single stick (unless you are planning to buy another matching 16GB stick in the near future to upgrade your RAM capacity further)
 

wardie

macrumors 6502
Aug 18, 2008
409
133
...and if you have the original apple factory RAM In the existing 2 slots out of 4, then it will be in the right places for dual channel operation. So just buy a pair of new ones and put them into the two spare slots (the other dual channel pair). No need to move the original ones.
 

vjaaan

macrumors 6502
Oct 13, 2010
346
8
But do all have to be of the same denomination. Like, 4 8s, or can you keep your original 2 4gbs and put two 16s in the 3rd and 4th slots.
 

wardie

macrumors 6502
Aug 18, 2008
409
133
But do all have to be of the same denomination. Like, 4 8s, or can you keep your original 2 4gbs and put two 16s in the 3rd and 4th slots.
Don’t all have to be the same. Pairs the same makes dual channel work, if in right slot pairs.
 
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