Memory upgrade troubleshooting in 2020 27-inch iMacs

[quagmire]

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!

I would say @Brookzy is the winner as that was the config suggested. I wasn't following the convo/didn't notice you two had 4 sticks of all the same size. That config would not work if the RAM was of different sizes hence my original comment of losing dual channel. If the config was 4x4x16x16 for example, it would be a loss of dual channel support. 4x16x4x16 would get dual channel back, but get that drop in speed.

But glad you got it figured it out.

 

[mikehalloran]

As mentioned earlier I think the problem is with mixing different sizes more than different brands.

I think you’re right. Many (most?) of us bought our machines with the 8GB minimum.


I came to this thread to learn a few things and my questions have been answered. Thanks to those who helped.

Last night, I installed the OWC RAM in my wife’s new Mac. 40GB at the rated speed following the 9to5 directions. Dual channel is not an issue on this machine with her uses — or maybe it is which I can test by swapping the sticks in slots 2 & 3. I will have plenty of real world tests I can run to see if it makes any difference at all—again, for her uses. Geekbench scores never factor into decisions like this—I want to see how such things affect the end user.

If I really think it makes a difference, I can always buy another pair of RAM from OWC. I’ve dealt with them enough over the last 35 years to know that, if I wound up with a quartet that weren’t perfectly matched, they’d make good.

 

[mikehalloran]

This is concerning. First time I’ve heard if you buy 2 pairs from the same vendor you can have the same issues as people are having with the original Apple memory.

This should no longer be a surprise. OWC and Crucial still list the 2019 and 2020 as taking the same RAM. The sites and other vendors need to update their information. I’m guessing that some RAM works in 2019s that isn’t completely compatible with 2020. It’s only a guess.

 

[Brookzy]

I wonder how many hours would have been saved if Apple just added

"For optimal performance in iMac (Retina 5K, 27-inch, 2020), do not mix RAM module size, manufacturer, or part number."

to the support document.

 

[mindquest]

IMac 2020 i9
5700 XT 16GB

OWC 4x16GB all bought at same time reporting 2667 MHz

Is the Geekbench score of 10012 good?

 

[KrazyKanuck]

IMac 2020 i9
5700 XT 16GB

OWC 4x16GB all bought at same time reporting 2667 MHz

Is the Geekbench score of 10012 good?

Golden!

 

[mindquest]

Golden!

Thanks wasn't sure what the ranges were for testing.

 

[Whiteman007]

Thanks wasn't sure what the ranges were for testing.

damn you got into the 10k range i have the same setup never hit that mark yet tho only 9.9k

my guess is that you have 64 gig ram while i have 32

 

[torifile]

2 runs. One with 40 gigs of RAM (8 OEM and 32 OWC)

The other, only 32 gigs of OWC

 

[drewski_t]

I wonder how many hours would have been saved if Apple just added

"For optimal performance in iMac (Retina 5K, 27-inch, 2020), do not mix RAM module size, manufacturer, or part number."

to the support document.

Yep that was my thought as well. It would have also helped if they’d told their own Product Specialists so I didn’t have to wait a week....

 

[Whiteman007]

2 runs. One with 40 gigs of RAM (8 OEM and 32 OWC) View attachment 946407

The other, only 32 gigs of OWC View attachment 946408

dont mix ram just use the 32. for some reason eith the new 2020 imacs when u mix with third party you either lose duel channel but keep the 2667 speed or you lose the 2667 speed but keep duel channel

 

[hellfried]

Have been following this whole thread since I got my 2020 iMac i5. Received my 2 x 8G of Crucial memory sticks yesterday and replaced the factory RAMs. Wonder if Apple is aware of this issue and if they will do something about it? Is it software or hardware related? Does the 2019 iMac behave this way?

 

[TiffMy]

There is one thing I am curious.
I have heard that Intel support Flex Memory mode, but I don’t know if iMac is different or not.
Will any one try to confirm it?

 

[quagmire]

Have been following this whole thread since I got my 2020 iMac i6. Received my 2 x 8G of Crucial memory sticks yesterday and replaced the factory RAMs. Wonder if Apple is aware of this issue and if they will do something about it? Is it software or hardware related? Does the 2019 iMac behave this way?

The 2019 iMac did not behave like this. I had 48 GB of RAM in my 2019 with two 8 GB sticks( Apple OEM) and 2 16 GB sticks( OWC). They were installed 16x8x16x8 in order to keep dual channel and kept full speed of the RAM.

 

[mindquest]

damn you got into the 10k range i have the same setup never hit that mark yet tho only 9.9k

my guess is that you have 64 gig ram while i have 32

I just added the Owc ram and ran the test. I am guessing the 64gb helped. Did 8 tests and all over 10k

 

[torifile]

dont mix ram just use the 32. for some reason eith the new 2020 imacs when u mix with third party you either lose duel channel but keep the 2667 speed or you lose the 2667 speed but keep duel channel

I understood that already. I was just posting more data to confirm the benchmark slowdown.

 

[mindquest]

We should start a thread to sell all this Apple RAM we are letting go to waste! lol

 

[Mr. Warbles]

Question:

I have an i7 8 core coming soon and 2 sticks of 32GB Samsung RAM.

I'm just going to ditch the stock Apple RAM to be safe but How should I configure the 2 3rd party sticks with the Apple RAM out? Just put the Samsungs sticks in slots 1 & 2?

 

[torifile]

Question:

I have an i7 8 core coming soon and 2 sticks of 32GB Samsung RAM.

I'm just going to ditch the stock Apple RAM to be safe but How should I configure the 2 3rd party sticks with the Apple RAM out? Just put the Samsungs sticks in slots 1 & 2?

To get dual channel working, you need to put the matching set in either slots 1 & 3 or 2 & 4.

 

[Mr. Warbles]

To get dual channel working, you need to put the matching set in either slots 1 & 3 or 2 & 4.

OK great! Exactly what I was looking for...definitely want dual channel. Thanks!

 

[Gmouse]

Geekbench Score
1287
Single-Core Score
9689
Multi-Core Score
Geekbench 5.2.3 for macOS x86 (64-bit)
System Information

System Information
Operating System	macOS 10.15.6 (Build 19G2021)
Model	iMac20,2
Model ID	iMac20,2
Motherboard	Apple Inc. Mac-AF89B6D9451A490B iMac20,2
BIOS	Apple Inc. 1037.147.4.0.0 (iBridge: 17.16.16610.0.0,0)

Processor Information
Name	Intel(R) Core(TM) i9-10910 CPU @ 3.60GHz
Topology	1 Processor, 10 Cores, 20 Threads
Identifier	GenuineIntel Family 6 Model 165 Stepping 5
Base Frequency	3.60 GHz
L1 Instruction Cache	32.0 KB x 10
L1 Data Cache	32.0 KB x 10
L2 Cache	256 KB x 10
L3 Cache	20.0 MB

Memory Information
Size	128 GB
Type	DDR4
Clock Frequency	1.33 GHz

 

[TheIntruder]

I wonder how many hours would have been saved if Apple just added

"For optimal performance in iMac (Retina 5K, 27-inch, 2020), do not mix RAM module size, manufacturer, or part number."

to the support document.

There is the possibility that the issues observed with the 2020 could be addressed with a firmware update.

I don't recall which machines they were, but there was a brouhaha in the past where an Apple update resulted in 3rd party RAM being declared incompatible, and ceased being recognized. That did not make users, who had been happily rolling along, to be less than pleased.

 

[koochyrat]

Crucial is the retail brand of Micron.

Could the real issue be mixing RAM sizes and not just brands? Has someone ordered two sticks of the latest Crucial the same size as the OE Micron and tested?

I did another test with all 3rd party RAM, and sure enough the speed went down to 2133MHz. Something like this would have worked fine with a PC, so it's just the iMac motherboard that's fussy. So it's not the Apple RAM, it's probably just the size and some other factor needs to match. I don't have anymore spare RAM sticks, so I can't test out more cases.

Removing the 8GB brings the speed back to 2667MHz.

 

[DCIFRTHS]

Micron is the company. Crucial is one of their retail brands.

Unless you are a VAR or OEM ordering directly, never buy RAM or SSDs under the Micron name. These are sold without warranty of any kind. The price to OEMs and VARs is low enough that they are expected to eat the occasional failure—OEM deals are normally structured that way. Micron is very upfront about this on their web site—if you have a problem, contact your vendor as there is no warranty from Micron. Unfortunately, you can find Micron branded RAM and SSDs all over Amazon and eBay etc.

Their Crucial brand has excellent customer service That I’ve experienced first hand.

I bought 20 Crucial MX300 2TB SSDs for clients. Every one of them developed issues during the 3 year warranty period. After emailing SMART reports, I received RMAs and shipped them off to their service center in Nampa, ID. The MX300 being discontinued, I received MX500s by return mail. As it should be.

The Micron 1100 is the exact same unit as the MX300. Imagine how much money I’d be out if I had bought 20 of those.

At the time, Crucial wasn’t a brand yet. It was Micron selling directly to the public. They created the Crucial Brand to sell directly to the public.

Micron used to advertise in Computer Shopper. This magazine was probably two inches think, and printed on thin phonebook-like paper. It wasn’t easy buying quality parts to build computers at the time.

Check out this link. Scroll to the bottom, and you’ll see that Crucial was created in 1996 to sell directly to the public. Its a cool company history in pics with short descriptions.

 

[PBG4 Dude]

LOL I remember the gamers column in the back of computer shopper where they were trying to achieve the holy grail of 640 x 480 @ 60FPS.