Memory upgrade compatibility list for iMac 2019-2020

[wilberforce]

Hello to everyone,

I live in Istanbul and i cant find the good seller and brands for this upgrades. I want to install 2x 32 GB RAM and upgrade to 64 GB RAM and get the best performance. Like everyone else I met many companies, but I did not get good results. I hope someone can help me!

My system:
Imac 2020 5K retina i7 3.8 - 8 Gb 2666 MHz DDR4

The products I could find:

• Kingston KVR26S19D8/32 32 GB DDR4 2666 MHz CL19 Ram (125$)
• Kingston 32GB DDR4 2666MHz CL19 Ram KCP426SD8/32 (210$)

What is the diffrence it looks the same? Which one is the best choice for my mac.


And also i found this one, link below. (230 $)

https://bilendenal.com/Bigboy-Apple-32GB-DDR4-2666MHz-CL19-Notebook-Rami-BTA026_32G.html

The seller said this brand has a samsung chipset and is 100% compatible with apple imac, but this is the first time I've heard of this brand.

Thanks!

Kingston says KCP426SD8/32 is compatible with the iMac.
Kingston KVR is Kingston's "ValueRAM," their lower cost RAM. Don't know if this will work just as well.

Best is if you can return whatever you buy, in case it does not work.

To test whatever you buy, I suggest Novabench RAM test, you should get 28,000+ MB/s RAM transfer speed.

 

[The French Man]

Hi,

Here is my bench with :
2 X HyperX Impact HX426S16IBK2/64 Mémoire 64Go Kit*(2x32Go)2666MHz DDR4 CL16 SOIMM

 

[Optimistprime]

Kingston says KCP426SD8/32 is compatible with the iMac.
Kingston KVR is Kingston's "ValueRAM," their lower cost RAM. Don't know if this will work just as well.

Best is if you can return whatever you buy, in case it does not work.

To test whatever you buy, I suggest Novabench RAM test, you should get 28,000+ MB/s RAM transfer speed.

Thank you!

 

[Megabass]

2 X HyperX Impact HX426S16IBK2/64 Mémoire 64Go Kit*(2x32Go)2666MHz DDR4 CL16 SOIMM

Hi.
I want to install modules of memory Kingston HyperX Impact HX426S16IB2K2/32 (2x16 GB) in the imac 27 2020. I did not find a mention of these modules here by search, but you wrote a positive review of the work of HX426S16IBK2/64 - unlike mine only in HX426S16IB2K2/32, not counting the amount of memory.
Do you think they will work?

 

[The French Man]

Hi,
I don't know why it will not ...
But in first don't use apple memory ; install modules of memory Kingston HyperX Impact HX426S16IB2K2/32 (2x16 GB) and boot with this modules only. On boot wait few seconds... be patient

 

[Megabass]

Thanks for the answer. Apple modules I do not plan to use

 

[Megabass]

Hi,
I don't know why it will not ...

After reading reviews on the Internet, I found reviews of memory modules HX426S15IB2K2/32 which said that they work perfectly on my imac. Unlike model HX426S16IB2K2/32 (DDR4-2666 CL16-18-18 @ 1.2V), the model S15 parameters DDR4-2666 CL15-17-17 @ 1.2V and it has a warranty of 5 years.
As a result, I bought memory for $135 HX426S15IB2K2/32 and it works great
Results novabench attached.
A smaller result with 8GB of memory, a larger result with 32GB of memory.
In addition to increasing memory speed, the speed of the CPU and GPU increased slightly.

 

[MarvinHC]

For information: Upgraded a 2020 iMac 27" (3.3Ghz) and it works perfectly fine with 4 of these:

CT2K16G4SFRA266​

Very cheap upgrade to 64 GB -> Cost me about 180 EUR vs. 1150 EUR from Apple!!!!

 

[Phil B]

Some answers:
1. Technically, you can add RAM in 2 slots and keep the 2x4GB in the other two slots, but memory speed will be degraded. Thus most prefer to remove the Apple RAM, as it is better to run the RAM at full speed, rather than have slightly more RAM all running at a lower speed. Short answer: you are correct.
2. Put 2x16GB in slots 2 and 4 (where slot 1 is at top).
3. 4x 8GB in all four slots will also work, but there is no advantage. (Some claim this is slightly faster, but that is very debatable, as the normal variation in test results is more than any perceptible difference). It will cost slightly more than 2x16GB, and also leaves you with no open slots if you want to add more RAM in the future.
4. The crucial kit that you cite is a good choice, and the M suffix indicates it is "for Mac" and guaranteed as such. However, many have used the non-M version with no problems, and surmise it is just marketing/environmental, as there does not appear to be any real substantive difference (maybe more testing). However, instead of 4x8GB, I would suggest this 2x16GB kit which is what i am using : CT2K16G4S266M

Crucial 32GB Kit (16GBx2) DDR4 2666 MT/s (PC4-21300) CL19 DR x8 SODIMM 260-Pin for Mac - CT2K16G4S266M

CT2K16G4S266M is a 32GB Kit consisting of (2) 16GB Dual Ranked DDR4 SODIMM modules that operates at speeds up to 2666 MT/s and has a CL19 latency. It is an Unbuffered SODIMM. It conforms to the industry standard DDR4 SODIMM layout of 260 pins and is compatible with systems that take DDR4 2666MT/s...

www.amazon.com

5. Many other kits work just as well. I tested this one and it was just as good, and is a great price, and is also guaranteed for Mac:

Timetec Hynix IC 32GB KIT(2x16GB) Compatible for Apple DDR4 2666MHz for Mid 2020 iMac (20,1/20,2) / Mid 2019 iMac (19,1) 27-inch w/Retina 5K Display, Late 2018 Mac Mini (8,1) PC4-21300/PC4-21333 RAM

Timetec Hynix IC 32GB KIT(2x16GB) Compatible for Apple DDR4 2666MHz for Mid 2020 iMac (20,1/20,2) / Mid 2019 iMac (19,1) 27-inch w/Retina 5K Display, Late 2018 Mac Mini (8,1) PC4-21300/PC4-21333 RAM

www.amazon.com

6. I actually suggest do not install the RAM before you turn it all on. Make sure it all works fine with the Apple RAM first. Then once everything is installed, running to your satisfaction, turn it off and switch out the RAM. Important note: after changing RAM, the Mac will take extra time to boot up, and appear to be completely black and unresponsive for an extra minute: do not worry, it is not broken! It is also quite easy to not get the RAM seated properly.
Hope this helps.

As I'm following the whole thread, cause planning to buy a new iMac 27, too, I'd just leave my 2 cents about the way you answered. Really kind, even with the tip to stay calm if something goes wrong etc. Always nice to see buddies around helping Mac Newbies this to welcome them in "our" family Cheers, Phil

 

[avxkim]

I just got 2x8GB OWC memory and i just ordered 2x8GB Timetec Hynix, specs wise they are equal, would this work together at 2667mhz?

nvm, i just canceled timetec order, getting OWC.

 

[1200RT]

I got the new kit CT2K32G4SFD8266 from Amazon today. After installation, the good news is the machine turned on and has been running fine so far. Bad news is after Geekbench I got a score of ~8200, a ~10% decrease compared to running with 64GB ram.

I checked, the memory is running at 2133 (with four sticks) instead of 2666 (with two sticks). I'm truly baffled now, all 4 sticks are exact the same from crucial (DDR4-2666, CT32G4SFD8266) with speed supporting 2666, just two CT2K32G4SFD8266 kits. What could have gone wrong here?

Looks like the kit CT2K32G4SFD8266 might indeed have compatibility issue with iMac 2020 after all? Can anyone else here with the kit verify their ram speed when all four slots are filled with this ram from crucial?

I might need to go for the "for Mac" kit CT2K32G4S266M for the best speed.

View attachment 976770

I just bought the 2020 IMac 27in. 5K with 8-core i7, 5700XT Gpu, 8 Gb ram, 2TB SSD

I purchased the Crucial CT2K16G4S266M- 4x16GB modules. I removed all of
the Apple ram and installed 2 of the Crucial modules in slots 1 & 3 and the computer wouldn’t even boot. Move these same 2 modules to slots 2 & 4 and it boots up and runs at 2667. When I add the remaining 2 identical ram modules, it cuts speed to 2133.
When using just the 2x4GB Apple modules alone, in slots slots 1&3 or 2&4 it boots and runs at 2667.
I called Crucial and they’re are pretty much clueless. Initially tried to tell me that I bought the wrong ram modules, even though I double checked it on their website.
They finally agreed these modules are the correct modules, but need 1 to 2 days to come up with their answer, when they will probably tell me to call Apple.

I have spent hours on this thread and others like it, and can’t find anywhere that someone has come up with an answer. Same brand, same size, same identical part number, and nothing works in this particular case when filling all 4 slots.

Anybody find a solution to this issue yet?

 

[avxkim]

4x8GB OWC sticks

 

[1200RT]

View attachment 1723592
4x8GB OWC sticks

So obviously it works for some people. Maybe I got 1 bad ram module and it’s throwing everything else off. I did try swapping modules 2&4 and 1&3 to no avail.
Then tried multiple combinations with moving the modules around. Then re tried putting 2 modules into slots 1&3 only, and once again it wouldn’t even boot. Moved those same modules to 2&4 and it boots and runs at 2667. Added back the last modules and once again it runs at 2133.
I don’t think it’s the computer, as it boots and runs at 2666 with the Apple ram in either a 1&3 or 2&4 combination, but then again it may not if I filled all 4 slots with same identical modules.
I guess I’ll send this Crucial ram back and try OWC or just get 2x32 Crucial modules and leave 2 slots open.
Kinda nuts that other people have had this same issue with even 4x32GB OWC modules running at 2133, and then removing 2 modules takes it back to 2666

 

[akbıyık]

I just upgraded my system to 128 GB with 4 x Timetec 78AP26NUS2R8-32G. They are not a kit, I bought 4 sticks in one order and they cost me half the price than any other brand. Surprisingly, they are more cheaper in my country than rest of the world.

I forgot to take photos of the sticks but there isn't any MADE FOR MAC indication anywhere on the sticks.
However when I search on Google by typing Timetec 78AP26NUS2R8-32G, every result shows that it is a MADE FOR MAC stick.

Anyway, first I put the sticks to the slots and tried to boot it up, but nothing happened for a good amount of time. I know that after powering it up, it stays 30 seconds or more to recognize the new sticks. So, I force shut down the imac and checked the sticks if there is any misplaced one. I pushed them down again and I think there was one didn't placed properly about half mm. I tried to boot it up and voila!

Btw, I brought Crucial sticks for my 5k 27" iMac 2015 in 2015 and they performed well at first. After a couple months they went dead with no reason but Crucial replaced them without asking a single question. I still use them. So, RAM failure might happen even if its the most reliable brand in terms of Mac memory.

Hope, these Timetec sticks work for many years without any problem.

I'll try to run some performance tests. After the tests, I'll share the results with you if everything goes without any problem.

 

[akbıyık]

I run the tests with 4 x Timetec 78AP26NUS2R8-32G and here they are.

Novabench: 402
Geekbench: 1230 - 10033

 

[juliano.arantes]

I've been running tests all afternoon and thought I'd share the results, since I haven't seem many people here reporting on Crucial CT16G4SFRA266.

So, long story short, I bought the officially homologated model which is CT16G4S266M but the vendor sent me CT16G4SFRA266 instead... I thought why not test it and see what happens.

iMac 2019
3,6 GHz 8-Core Intel Core i9
Radeon Pro 580X 8 GB
Apple 512GB SSD Hard Disk

Geekbench Results:

8GB TOTAL - 2x 4GB APPLE STOCK (HYNIX BTW) - 6571
32GB TOTAL - 2x 16GB CRUCIAL CT16G4SFRA266 - 7606
40GB TOTAL - 2x 4GB APPLE + 2x 16GB CRUCIAL - 7228

Not sure why I had a small drop in performance when using them all together, one possibility was that I lost dual channel, so I ran the test again with the memories paired wrongly on purpose, with Apple ones in slots 1-2 and Crucial in slots 3-4.

40GB TOTAL - 2x 4GB APPLE + 2x 16GB CRUCIAL - PAIRED WRONGLY - 6153

So it's quite obvious that now I did lose dual channel, and before I still had it, the answer to why I lost performance on Geekbench when mixing memories remains unanswered. Any ideas?

Than I ran Novabench as a second opinion with same setups, just to make sure I could make the best decision:

8GB TOTAL - 2x 4GB APPLE STOCK (HYNIX BTW) - 224 (25118 MB/s)
32GB TOTAL - 2x 16GB CRUCIAL CT16G4SFRA266 - 315 (27530 MB/s)
40GB TOTAL - 2x 4GB APPLE + 2x 16GB CRUCIAL - 327 (27149 MB/s)

40GB TOTAL - 2x 4GB APPLE + 2x 16GB CRUCIAL - PAIRED WRONGLY -295 (17830 MB/s)

So I guess it's possible to conclude that at least on the 2019 iMac, Crucial #CT16G4SFRA266 is also an option. Second important conclusion is that it works on dual channel even when mixing with the stock Apple/Hynix modules. I'll leave it with 40GB and simply disregard the small drop reported by Geekbench, as I do a lot of 4K video editing and could use as much RAM as I had.

I've been researching the differences between the CT16G4SFRA266 and the previously reported here CT16G4SFD8266 and couldn't find any. The only hint I got was from the B&H Photo Video website, which listed the SFD8 as discontinued and stated that the FRA is the sucessor. Can anyone confirm that?!

I've attached screenshots for those who want to check it out, hope the information helps as this thread has been my number one source for the 2019 iMac RAM doubts.

Quick EDIT: CRUCIAL website lists the CT16G4SFRA266 as incompatible with the 2019 iMac, but at the same time says it's compatible with the MacMini 2018... And as another user has pointed out Apple uses the same memory for both!

 

[wilberforce]

So it's quite obvious that now I did lose dual channel, and before I still had it, the answer to why I lost performance on Geekbench when mixing memories remains unanswered. Any ideas?

I don't know if you ran Geekbench several times, but my best guess is there was some background process running during the 40GB test, and suggest try it again.
Everything else looks OK, should be fine to use 40GB in a 2019 iMac - paired correctly so that each channel has same amount of RAM as the other channel.
I assume you have confirmed from System Report, Memory, that all sticks are running at 2667MHz.

 

[juliano.arantes]

I don't know if you ran Geekbench several times, but my best guess is there was some background process running during the 40GB test, and suggest try it again.
Everything else looks OK, should be fine to use 40GB in a 2019 iMac - paired correctly so that each channel has same amount of RAM as the other channel.
I assume you have confirmed from System Report, Memory, that all sticks are running at 2667MHz.

Now that I'm reading you say it, sounds pretty obvious. But that was my first time using Geekbench!

I've restarted every time to give it a "fresh start", but only ran once. Waited a couple minutes but probably had some background processes still initializing. And yes, I've confirmed from System Report that they always run at 2667MHz no matter how I mount them.

 

[alissonss]

Hello everyone!

I'm looking for upgrading the RAM of my iMAC 2020 27". I have a question about it: Do I need to install always pairs of memory cards (2x16GB) or it's possible to use only one card (1x32GB)?

Thanks!

 

[longtom]

You can also use only one bank.

 

[wilberforce]

Hello everyone!

I'm looking for upgrading the RAM of my iMAC 2020 27". I have a question about it: Do I need to install always pairs of memory cards (2x16GB) or it's possible to use only one card (1x32GB)?

Thanks!

It is much better to use pairs of matched memory cards, one in each channel, than a single card.
Reason is that the memory controller accesses each channel simultaneously, thus effectively doubling the memory transfer speed.
If you only use one card, you effectively halve your memory transfer speed.

 

[hoodafoo]

Still can't believe I scored 64GB of Crucial DDR4 for $170 on Amazon prime day last year

 

[unkyp]

Hi all,

I have a imac 27, mid 2020. I upgraded the stock ram with CT2K32G4S266M and now wondering if I can add CT2K32G4SFD8266 to make it a beast with 128gig ram. The specs are identical and I don't see why CT2K32G4SFD8266 wouldn't work, however, just wondering if anyone has tried to mix the crucial mac compatible ram with the CT2K32G4SFD8266 one and whether it is still giving the full 2666 speed or its 2133? Also, has anyone used 128gig of CT2K32G4SFD8266 to check if it works to max speed?

I am getting 50% off on CT2K32G4SFD8266 via. amazon (BF2021), just wondering if its worth the hassle?

 

[wilberforce]

Hi all,

I have a imac 27, mid 2020. I upgraded the stock ram with CT2K32G4S266M and now wondering if I can add CT2K32G4SFD8266 to make it a beast with 128gig ram. The specs are identical and I don't see why CT2K32G4SFD8266 wouldn't work, however, just wondering if anyone has tried to mix the crucial mac compatible ram with the CT2K32G4SFD8266 one and whether it is still giving the full 2666 speed or its 2133? Also, has anyone used 128gig of CT2K32G4SFD8266 to check if it works to max speed?

I am getting 50% off on CT2K32G4SFD8266 via. amazon (BF2021), just wondering if its worth the hassle?

I have not tried these specific part numbers, but yes, you can mix two different part numbers in the 2020 iMac, provided the DIMMs are all the same size and specs, but instead of the usual order in the slots 1,2,3,4: ABAB, you will likely need to install them in the order: AABB
A = the one part number
B = the other part number

The 2020 iMac wants to see the same part # in slots 1 and 2, and the same part # in slots 3 and 4, otherwise speed drops to 2133. (A weird quirk of the 2020 iMac.)

To get full dual channel, the total size in Channel A (slots 1+2) must equal the total size in Channel B (slots 3+4).

The only way to satisfy both these requirements, if using two different part numbers, is to have all DIMMs the same size and installed in order AABB.

I have confirmed this on my 2020 iMac (but not with your specific part numbers).

I am 99.9% sure it will work fine, but suggest make sure it is returnable (Crucial usually is).

btw, I suspect your iMac will only be about 1% more beastly with this upgrade, but maybe you have extraordinary RAM needs

 

[hoodafoo]

it's been over a year since we had this issue of downgrading ram speed by mixing and matching ram sizes. Maybe firmware updates since then has made this a thing of the past