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Memory upgrade compatibility list for iMac 2019-2020

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The first post of this thread is a WikiPost and can be edited by anyone with the appropiate permissions. Your edits will be public.
Neoaf said:
According to this webiste above-mentioned memory chip is 3200Mhz. So maybe 3200Mhz memory chips would work correctly with these and maybe this is why 2666Mhz ones are causing problems?

EDIT:
Unfortunately I was unable to find 3200Mhz 8GB DDR4 CL19 SO-DIMM RAM for sale
Click to expand...
No. the -VK model is the 2666 MHz and this is the required module.
 
Wondering if I can get thoughts on a 128gb kit. I guess only OWC has one listed in the first post. What do you think of OWC memory?

The Crucial stuff is confusing. Could I just order two 64gb kits? (2 x CT2K32G4S266M)? There's also CT2K32G4SFD8266 but still not clear what the difference is there between those two. CT2K32G4S266M is out of stock in Amazon. I prefer Amazon due to easy return if it doesn't work.
 
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bigcat said:
Wondering if I can get thoughts on a 128gb kit. I guess only OWC has one listed in the first post. What do you think of OWC memory?

The Crucial stuff is confusing. Could I just order two 64gb kits? (2 x CT2K32G4S266M)? There's also CT2K32G4SFD8266 but still not clear what the difference is there between those two. CT2K32G4S266M is out of stock in Amazon. I prefer Amazon due to easy return if it doesn't work.
Click to expand...

OWC is fine.

But Crucial is number one for me. Order it directly on Crucial if Amazon is out of stock.
 
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Are these compatible to run in dual channel full speed together with the Apple's stock ram?
ie. if i get 2x16 and then keep the 2x4 from Apple I get 40gb total and no issues, please?

pldelisle said:
Since many people were asking which RAM modules they could use to upgrade the 2019 or 2020 iMac, here are once and for all the compatible memory modules for both models. Feel free to add any kits you personally tested.



Memory upgrade compatibility list for iMac 2019-2020​


Compatible Crucial part numbers :

See the 2666 MT/s modules in Crucial Memory for Mac Systems


Compatible Kingston part numbers :


Compatible OWC part numbers :


Compatible Samsung part numbers:


Compatible SK Hynix part numbers :

* Not confirmed, but seems the only other model available on SK Hynix website. Shares same 1Gx64 or 2Gx64 organization spec as the original Apple RAM.

iMac 2019-2020 needs :
  • PC4-21333
  • Unbuffered
  • Nonparity
  • 260-pin DR (Dual Ranked) or SR (Single Ranked)
  • 2666MHz
  • CL19
  • 1.2v
  • Source : Install memory in an iMac.


See Installation instructions upon receiving your RAM module(s).
Click to expand...
 
Freida said:
Are these compatible to run in dual channel full speed together with the Apple's stock ram?
ie. if i get 2x16 and then keep the 2x4 from Apple I get 40gb total and no issues, please?
Click to expand...
Many reports that memory falls to 2133 MHz when mixing anything with stock Apple RAM.

I don't think it's possible to mix anything with the stock RAM. Mac is shipped with SK Hynix RAM specifically for it. It's virtually impossible to buy the same RAM aftermarket. So I would sell the stock modules to someone who wants 16 GB in its iMac (this will obviously work because it would have the same stock modules) and get all-Crucial memory kits.
 
pldelisle said:
No. the -VK model is the 2666 MHz and this is the required module.
Click to expand...

Ok. Thank you.

So I checked on Hynix's website what SODIMM RAM they are offering right now and I got this:
Zrzut ekranu 2020-08-18 o 18.48.02.png

Apparently the letter before "JR6N" shows on what die (whatever that is) memory chip is based on. So HMA851S6DJR6N-VK (which is the model present in the base model iMac 2020 as stated above in this thread) is based on D-die (according to its technical data sheet) and the HMA81GS6CJR8N model I mentioned before is based on C-die (according to its technical data sheet).

Therefore judging by the information provided on Hynix's website - most similar 8GB RAM chip to the RAM which Apple is putting in the iMac is the HMA81GS6DJR8N-VK model.

I will buy two 8GB chips of those and try to run 24GB of RAM on 2666Mhz. Wish me luck haha

PS. I wonder what memory chips is Apple putting into the iMac 2020 configured with 16GB of RAM. 4x 4GB? 2x8GB? What model of 8GB?
 
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Neoaf said:
Ok. Thank you.

So I checked on Hynix's website what SODIMM RAM they are offering right now and I got this:
View attachment 945202
Apparently the letter before "JR6N" shows on what die (whatever that is) memory chip is based on. So HMA851S6DJR6N-VK (which is the model present in the base model iMac 2020 as stated above in this thread) is based on D-die (according to its technical data sheet) and the HMA81GS6CJR8N model I mentioned before is based on C-die (according to its technical data sheet).

Therefore judging by the information provided on Hynix's website - most similar 8GB RAM chip to the RAM which Apple is putting in the iMac is the HMA81GS6DJR8N-VK model.

I will buy two 8GB chips of those and try to run 24GB of RAM on 2666Mhz. Wish me luck haha

PS. I wonder what memory chips is Apple putting into the iMac 2020 configured with 16GB of RAM. 4x 4GB? 2x8GB? What model of 8GB?
Click to expand...
Good luck.

100% sure it’s 4x4. Apple can buy higher number of modules from Hynix so it saves more.
 
pldelisle said:
I don't see why it shouldn't work. They have the exact same specs... Maybe the chat guy just read his sheet of paper.
Click to expand...
Yeah, I'm thinking the same.It makes zero sense to me that it shouldn't work if the specs are identical.

Maybe I will take one for the team and actually try them out...
 
imac2020 said:
Yeah, I'm thinking the same.It makes zero sense to me that it shouldn't work if the specs are identical.

Maybe I will take one for the team and actually try them out...
Click to expand...

when you click on "full specs", these were the only differences I noticed:

CT2K32G4S266M:
PC speed - PC4-21300 (peak data transfer rate MB/s)
2048Meg x 64 • lead free • halogen free • for Mac

CT2K32G4SFD8266:
PC speed - PC4-25600 (peak data transfer rate MB/s)

I guess it could be a typo; or maybe they just peak differently, even tho they are both PC4-21300, no idea.
 
bigcat said:
when you click on "full specs", these were the only differences I noticed:

CT2K32G4S266M:
PC speed - PC4-21300 (peak data transfer rate MB/s)
2048Meg x 64 • lead free • halogen free • for Mac

CT2K32G4SFD8266:
PC speed - PC4-25600 (peak data transfer rate MB/s)

I guess it could be a typo; or maybe they just peak differently, even tho they are both PC4-21300, no idea.
Click to expand...

It's a different JEDEC programmation within the DRAM chips.
 
What are your thoughts on this memory for a 2020 27" iMac?

www.hyperxgaming.com

HyperX | High Quality Gaming Gear

HyperX is a brand committed to making sure every gamer feels they are included. No matter who you are, or what you play, WE'RE ALL GAMERS.
www.hyperxgaming.com www.hyperxgaming.com

The 2666Mhz is on sale for $194 for 64GB (2x32GB)
 
ZBoater said:
What are your thoughts on this memory for a 2020 27" iMac?

www.hyperxgaming.com

HyperX | High Quality Gaming Gear

HyperX is a brand committed to making sure every gamer feels they are included. No matter who you are, or what you play, WE'RE ALL GAMERS.
www.hyperxgaming.com www.hyperxgaming.com

The 2666Mhz is on sale for $194 for 64GB (2x32GB)
Click to expand...

Not compatible. Please refer to first post for all Kingston certified compatible modules.
 
pldelisle said:
I wouldn't take any chance. Anyway, you don't need HyperX branded RAM. The Kingston ValueRAM is plenty enough.
Click to expand...

Normally I would agree. I am not looking to overclock the RAM. But at $194 for 64GB that is a pretty good deal. Cheapest I can kind Valueram is $300 for 64GB. That a $100 difference.
 

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ZBoater said:
Normally I would agree. I am not looking to overclock the RAM. But at $194 for 64GB that is a pretty good deal. Cheapest I can kind Valueram is $300 for 64GB. That a $100 difference.
Click to expand...
Well, try it to see if it works. if not, return them and take ValueRAM.

I wouldn't try if it was my money. It's your call.
 
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Can someone help with a working version to add another 8GB to the standard version iMac to bring it to 16GB? Something to keep the dual channel, so 2 x 4GB modules.
 
I got my 2 sticks of CT32G4SFD8266 today, which the Cruical website said wouldn't work.

I decided to try them out, replaced the 2x4gb with the new sticks. Originally thought I would keep the original 8gb, but due to the experiences from the other tread I decided to leave them out.

Machine booted ok, no problems so far.

Ran the Geekbench cpu & compute tests before/after:

stock 8gb
Single-core 1245
Multi-core 8109
Open-CL 57299

new 64gb
Single-core 1267
Multi-core 9991
Open-Cl 51199

Ran Open-Cl a second time due to the big difference, got 54107...
Open-Cl #3rd 54772
Open-Cl #4th 56199

Thought GeekBench was decent, not sure why it is all over the place in the compute test?
 
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