Dual Channel DRAM Questions

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I just purchased a new iMac with the default 8GB RAM. I am going to purchase 32GB (16x2) but have a couple of questions about making sure it runs dual channel.

Question 1 - Do I need to purchase as "paired" 16x2 or if I purchase 2 of the same 16x1 will it be paired. Basically, is there anything doen at the memory factory to "pair" them. The reason I ask is because the Crucial memory I am looking at on Newegg is $365 for 16x2 and $167 for 16x1. So purchasing 2 16x1 of the same memory is $30 less than purchasing it as 16x2.

Question 2 - If I put in the 16x2 and leave in the 4x2 will it still run dual channel as 40GB?
 
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G'day and welcome to mthe forums.

I always go for matched pairs from OWC. A matched pair of 16GB modules comes in at $334.00, a little saving. Have a look at this link:-


https://eshop.macsales.com/shop/memory/imac-2017-27-inch

Thanks for the link. I will just go with that one. Just curious, do you know what is involved for matching? Does it just mean that it is the same memory make/model to make it matching? Or is there some other matching beyond just 2 of the same parts that done at the memory factory?
 

Raz0rEdge

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Your Mac's Specs
2022 Mac Studio M1 Max, 2023 M2 MBA
There's nothing special about "matched" pairs other than the fact that they are similar in configuration (size, speed, latency, and so on).
 
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Thanks. I ordered the memory. What about keeping the 2x4 installed and adding the 2x16. Will it still run as dual channel? Or do all cards needs to be exactly the same?
 

Raz0rEdge

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That should be totally fine. All of the memory will be detected. The primary thing is to ensure that the speed/refresh is matched all around. If you don't do that, then the memory bus will throttle down to the slowest memory and you won't be taking advantage of faster memory. OWC will sell you the exact memory you need for each Mac that will ensure top performance.
 

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