Memory upgrade troubleshooting in 2020 27-inch iMacs

[quagmire]

I think we can establish a rule of thumb here with the 2020 iMac for now.

1. If putting 4 sticks of the same size in, put the matched pairs in the adjacent slots( ie 1 and 2 and 3 and 4).

2. if putting just 2 sticks in the machine, put in either slots 2 and 4 or 1 and 3.

3. Don’t mix different sizes of RAM. But if you must, keeping dual channel is better than restoring full speed. So put the same size sticks in 2 and 4 and the other size in 1 and 3.

 

[Ludimus]

I picked up 2x4GB of those "wasted" sticks from an Imac 2020 for $18 bucks.
And going for 4x4x4x4. I think it should clock to 2666 with dual channel performance.
Will report when the imac arrives (in 10 days)

OK this works (as expected). All 4 apple sticks running at 2666

GB5 scores (middle imac 2020 6-core i5)

base config 8GB: 1204/5820
upgraded config (4x4GB): 1203/6452

 

[wilberforce]

I think we can establish a rule of thumb here with the 2020 iMac for now.

1. If putting 4 sticks of the same size in, put the matched pairs in the adjacent slots( ie 1 and 2 and 3 and 4).

2. if putting just 2 sticks in the machine, put in either slots 2 and 4 or 1 and 3.

3. Don’t mix different sizes of RAM. But if you must, keeping dual channel is better than restoring full speed. So put the same size sticks in 2 and 4 and the other size in 1 and 3.

This is a good summary

 

[jiminoz]

And you are the winner! So I just put the first pair in 1 and 2, and the second pair in 3 and 4, and they are now listed as 2667! Also, I am posting an image, the first two tests are in the original.

Also if you look at the ram, then are physically two completely different types of modules. I didnt compare them before I put them in I just assumed they were the same. They are not even though both from OWC.
View attachment 946326 View attachment 946330 placement rated at 2166, and the third screenshot (higher) is the new placement and is listed at 2667MHZ!

You have EXACTLY the same ram I have. I bought 2x16 from OWC and the first were assembled in Mexico. Then I ordered 2x16 more and they were assembled in Taiwan. When I put them in MTMT, I got 2133MHz, then MMTT it was at 2667. My speeds are similar to yours. Also on NovaBench, the scores look acceptable.

I contacted OWC who agreed to take the ram back. If I do that, I will buy 2x32 from them. However, I am not sure if this can be improved, and after reading many pages, I cannot be sure if I have dual channel or not. I am in Australia, so I would cost $25 to have new ram shipped here and probably that for me to ship the old back, so I am not sure it is worth it.

 

[wilberforce]

You have EXACTLY the same ram I have. I bought 2x16 from OWC and the first were assembled in Mexico. Then I ordered 2x16 more and they were assembled in Taiwan. When I put them in MTMT, I got 2133MHz, then MMTT it was at 2667. My speeds are similar to yours. Also on NovaBench, the scores look acceptable.

I contacted OWC who agreed to take the ram back. If I do that, I will buy 2x32 from them. However, I am not sure if this can be improved, and after reading many pages, I cannot be sure if I have dual channel or not. I am in Australia, so I would cost $25 to have new ram shipped here and probably that for me to ship the old back, so I am not sure it is worth it.

These are perfect scores and RAM speed for an i7.

 

[getrealbro]

I think we can establish a rule of thumb here with the 2020 iMac for now.

1. If putting 4 sticks of the same size in, put the matched pairs in the adjacent slots( ie 1 and 2 and 3 and 4).

2. if putting just 2 sticks in the machine, put in either slots 2 and 4 or 1 and 3.

3. Don’t mix different sizes of RAM. But if you must, keeping dual channel is better than restoring full speed. So put the same size sticks in 2 and 4 and the other size in 1 and 3.

Thanks for the concise summary.

If I understand correctly — if you add a matched pair of 16GB 2667GHz RAM sticks to a 2020 iMac, you can either have:
- 40 GB of RAM at only 2133MHz, but dual channel
or
- 32 GB of RAM at 2667MHz, and dual channel — with 8GB of RAM “spare”.

SO… the only way you can use the original 8GB of Apple RAM at full speed is to add 2 more 8GB sticks yielding only 16GB of total RAM but at 2667 MHz and dual channel. IOW for most people who buy a 2020 iMac, the original 8GB of Apple RAM is only really useful for testing & configuring their new iMac prior to upgrading the RAM

GetRealBro

 

[anthony13]

Thanks for the concise summary.

If I understand correctly — if you add a matched pair of 16GB 2667GHz RAM sticks to a 2020 iMac, you can either have:
- 40 GB of RAM at only 2133MHz, but dual channel
or
- 32 GB of RAM at 2667MHz, and dual channel — with 8GB of RAM “spare”.

SO… the only way you can use the original 8GB of Apple RAM at full speed is to add 2 more 8GB sticks yielding only 16GB of total RAM but at 2667 MHz and dual channel. IOW for most people who buy a 2020 iMac, the original 8GB of Apple RAM is only really useful for testing & configuring their new iMac prior to upgrading the RAM

GetRealBro

Yes this appears to be the case. The only reason I've been able to keep my apple ram is that they were 16GB sticks, and I added two more aftermarket 16GB sticks.

 

[hellfried]

I just realised that the MacBook Air 2020 base model has faster RAM then the 2020 iMac. And here we are discussing the max speed achievable with the iMac. Wonder what went into the decision to include slower RAM in what is supposedly a higher end machine when compared to the MBA.

 

[Camazza]

I just realised that the MacBook Air 2020 base model has faster RAM then the 2020 iMac. And here we are discussing the max speed achievable with the iMac. Wonder what went into the decision to include slower RAM in what is supposedly a higher end machine when compared to the MBA.

Simple, Ice Lake (Mobile-only 10xxGx series) supports 3733mhz RAM, Comet Lake (Desktop 10 Series) does not. It does, however, support up to 2933Mhz RAM yet they chose 2666.

EDIT: The i5 only supports 2666Mhz RAM, so they probably went with 2666 across the whole range to simplify manufacturing. Too bad the higher clockspeed is entirely unavailable even with the proper sticks.

 

[myjacob]

Base iMac 2020 Is working great with HyperX Impact 2x16GB. ( Hynix CRJ’s chips ). I need to say that I’m pretty happy with Radeon Pro 5300. This GPU is really close to Desktop 5500XT 4GB. Geekbench 5 scores:

 

[minik]

Base iMac 2020 Is working great with HyperX Impact 2x16GB. ( Hynix CRJ’s chips ). I need to say that I’m pretty happy with Radeon Pro 5300. This GPU is really close to Desktop 5500XT 4GB. Geekbench 5 scores:

After everything looked good on the 2020 iMac, I try Windows 10 (BootCamp) on my late 2015 iMac. It turned out the stock graphics driver from Apple was much older and I realized AMD has a dedicated download page for BootCamp Windows users. Apple Boot Camp Software Graphics Drivers Which driver did Apple supply on the new 2020 model?

 

[pldelisle]

I don't know, but

• MacBook Pro (Retina, 16-inch, 2020) with Radeon Pro 5600M

should work with 2020 iMac. It's basically the exact same chip.

 

[SteveR123]

New iMac i9. installed 4x16gb OWC memory. Computer wouldn't boot.
Took two of them out and put them in 1/3 and then again 2/4. It booted.
Called OWC and said two sticks must be bad, so they sent me 4x16 more.
Tried all 8 sticks in various ports and it won't boot.

Most I can get is 2x16gb out of the entire set.

Should I return the computer? Bad slots? Or is it for sure the memory?

Seems odd that 8 sticks from the same manufacturer can't get 4 of them to work.

Steve

 

[pldelisle]

New iMac i9. installed 4x16gb OWC memory. Computer wouldn't boot.
Took two of them out and put them in 1/3 and then again 2/4. It booted.
Called OWC and said two sticks must be bad, so they sent me 4x16 more.
Tried all 8 sticks in various ports and it won't boot.

Most I can get is 2x16gb out of the entire set.

Should I return the computer? Bad slots? Or is it for sure the memory?

Seems odd that 8 sticks from the same manufacturer can't get 4 of them to work.

Steve

Really weird.... Does all 4 have the same ICs ? If you look on them, is it all Micron or all Hynix memory?

 

[SteveR123]

Really weird.... Does all 4 have the same ICs ? If you look on them, is it all Micron or all Hynix memory?

They are all sequential serial #'s and the IC's all look identical. I can't see a name of a manufacturer on them.
SEC928
KuA8G08

 

[pldelisle]

Ok ... I can't understand. Can you ask a refund at OWC and try another brand like Samsung or Crucial ? I doubt it would be the iMac seriously...

 

[SteveR123]

Ok ... I can't understand. Can you ask a refund at OWC and try another brand like Samsung or Crucial ? I doubt it would be the iMac seriously...

I'm on hold with them now.. 20+ minutes. Yes I can try another brand. I have always held them in high regard. This thread doesn't seem to indicate any brand that is working for all four slots aside from one lucky guy from OWC. Maybe I just missed it.

Steve

 

[pldelisle]

I'm on hold with them now.. 20+ minutes. Yes I can try another brand. I have always held them in high regard. This thread doesn't seem to indicate any brand that is working for all four slots aside from one lucky guy from OWC. Maybe I just missed it.

Steve

I think OWC is a really, really overrated company. Better to chose Crucial or Kingston. Crucial is even better because it has only one manufacturer : Micron. Kingston may vary between Micron and Hynix, thought the "For Mac" is usually a fixed BOM.

 

[SteveR123]

I think OWC is a really, really overrated company. Better to chose Crucial or Kingston. Crucial is even better because it has only one manufacturer : Micron. Kingston may vary between Micron and Hynix, thought the "For Mac" is usually a fixed BOM.

Ok.. here is the latest.... maybe it will help someone.

OWC Tech support was very helpful.

We installed the two sticks we knew worked.
Then added a third. Took a while to boot.
Then added a fourth..Wouldnt boot.
Then used a fourth from the second set of 4 I had them send and it gave me the "No smoking sign" on the Apple after we booted.
He had me just do another reboot and it worked.

We have 4x16 sticks working, all at 2667 now. 3 from the first batch and the fourth from the second. They were all manufactured in Taiwan, although the guy I spoke to said they assemble them in Mexico.

Best of luck and thanks for the feedback.
Steve

 

[pldelisle]

Ok.. here is the latest.... maybe it will help someone.

OWC Tech support was very helpful.

We installed the two sticks we knew worked.
Then added a third. Took a while to boot.
Then added a fourth..Wouldnt boot.
Then used a fourth from the second set of 4 I had them send and it gave me the "No smoking sign" on the Apple after we booted.
He had me just do another reboot and it worked.

We have 4x16 sticks working, all at 2667 now. 3 from the first batch and the fourth from the second. They were all manufactured in Taiwan, although the guy I spoke to said they assemble them in Mexico.

Best of luck and thanks for the feedback.
Steve

what the f.... ahahahah

 

[Lisse]

When I started looking at adding memory to my new 27” iMac I went to the Apple site and read about how to physically add it to computer. I thought I read it thoroughly, but I don’t remember reading anything that said “For optimal memory performance, DIMMs should be the same capacity, speed, and vendor.”

That’s what it said today when I was still trying to figure out if it’s even worth doing anything to get both the third party DIMMs I purchased and the minimum amount of memory with which the computer came.

I wonder if Apple has added this line after the past few weeks of disenchantment that people are voicing here — and probably to Apple itself.

OTOH, if I’d known that I couldn’t mix Apple and third party memory, would I have done anything differently? Apple sure makes it tough to stick with them when they charge three or more times as much as memory from other vendors.

 

[KrazyKanuck]

When I started looking at adding memory to my new 27” iMac I went to the Apple site and read about how to physically add it to computer. I thought I read it thoroughly, but I don’t remember reading anything that said “For optimal memory performance, DIMMs should be the same capacity, speed, and vendor.”

That’s what it said today when I was still trying to figure out if it’s even worth doing anything to get both the third party DIMMs I purchased and the minimum amount of memory with which the computer came.

I wonder if Apple has added this line after the past few weeks of disenchantment that people are voicing here — and probably to Apple itself.

OTOH, if I’d known that I couldn’t mix Apple and third party memory, would I have done anything differently? Apple sure makes it tough to stick with them when they charge three or more times as much as memory from other vendors.

Good catch! I don't recall that text being on the site earlier. If you look at the bottom of the page it says published on "September 02, 2020". It also appears that the text "For optimal memory performance, DIMMs should be the same capacity, speed, and vendor" is unique to only the 2020 iMacs. Hmm...

Install memory in an iMac - Apple Support (CA)

Get memory specifications and learn how to install memory in iMac computers.

support.apple.com

 

[SteveR123]

Good read-

2020 iMac 5K 8-core - memory tester

real world speed test results for performance minded Macintosh users

barefeats.com

 

[costica1234]

Wow, so they updated the US / Canadian support pages, but not the UK-based one: https://support.apple.com/en-gb/HT201191. Searching for 'vendor' doesn't return anything!

 

[Kotomoto]

Hello guys, i have 2020 iMac

I have 2x4gb Hynix, and 2x4gb Micron ram, (16gb total)

if I put Micron-Hynix-Micron-Hynix the speed downgrades to 2133

Do I need to put Micron-Micron-Hynix-Hynix to keep 2666? Will I keep dual channel with this setup?

Thanks for answer friends!