Memory upgrade troubleshooting in 2020 27-inch iMacs

[KrazyKanuck]

Have you tried booting into windows to see if there is a difference with the different OS?

Excellent question. I have not.

 

[Robejazz]

Hi all. I read through this and I’m looking for some advice too. Not sure why I’m sweating these details...but I am

i have the tier 3 base config ... I took out the 2 x 4 GB sticks and replaced them with 2 x 16 GB sticks from OWC ... I am seeing the 2667 number and my report shows the RAM in slots 2 and 4 and 2 slots are open.
I teach and spend most of my time in Zoom, screenflow, word, keynote and chrome apps ... whats your advice ? Keep it this way ? Add the Apple RAM back in the 9to5 Mac way ?
thanks

 

[Fred Zed]

Sorry, haven't difficulty following all this as I'm not that technical. What was the final recommendation? I bought the extra 32GB from OWC and had plan to add it to Apple's 8GB for a total of 40GB. My needs are relatively basic.

Put the Apple stock ram in a bag and just use you’re aftermarket ram

 

[Robejazz]

Put the Apple stock ram in a bag and just use you’re aftermarket ram

That's what I opted for too

 

[Fred Zed]

That's what I opted for too

Same here cuz

 

[DrRadon]

You are trashing 8gb just like that?

From my cluelessness and short google searches it seems like dual chanel is mostly important if you have no dedicated GPU.

 

[jacklivehere]

I went with Samsung memory from amazon with one day free delivery. Works great. Bought 2x32gb

Samsung 32GB DDR4 2666MHz RAM Memory Module for Laptop Computers (260 Pin SODIMM, 1.2V) M471A4G43MB1

 

[Fred Zed]

I feel your pain. Your question about the T2 is beyond my level of knowledge, but a few of us have run benchmarks confirming a performance penalty when running both Apple OEM RAM and 3rd party RAM, and which seem to be independent of the particular brand of 3rd party RAM.

Indeed. Just to clarify for others on here. My initial Geekbench test figures ( multicore and singlecore )with the stock 8GB RAM was similar to when I installed the additional 32GB Crucial memory using the 9to5 Mac method totaling 40GB.

However, once I removed the stock 8GB and paired the two 16GB crucial memory modules totaling 32GB my Geekbench scores increased significantly.

 

[8ght]

I bought 2x16GB Crucial CT2K16G4S266M initially meant for a 2019 iMac. I swapped the iMac for the i7 2020 version since it was released during my return period.

Sadly the RAM runs at 2133MHz on the 2020 iMac when running together with the original Apple RAM Hynix HMA851S6DJR6N. They ran on the expected speed on the 2019 iMac though. Let me know if you have any better luck @DrRadon.

Is there a free version of Geekbench or do you have to buy a license @Limeybastid?

 

[DQ11]

Interesting. Thanks for sharing this. I wouldn't have though that it would be THAT particular about about RAM. I received my second pair of Crucial RAM yesterday and tried it with the original Apple RAM. I got the same result as the first batch of Crucial I tried with Apple RAM. I'm now using four sticks of Crucial for 32GB at 2667. I did configure it though so that the first pair that I received is in DIMM 0 and the second in DIMM 2. This restored dual channel (vs. Crucial in channel A and Apple in B) and the performance is now as expected.

How can you check to see if it restores dual channel?

 

[DQ11]

I have the new i7 8-core model. Came with 8GB. 32GB (2x16) added.

When installed in the order 4-16-4-16 or 16-4-16-4 the system reports 2166MHz memory speed. Geekbench 5 results are 1270 for single-core and 8400 for multi-core.

When installed in the order 16-16-4-4- the system reports 2400MHz memory speed (!). However multi-core Geekbench results drop to 6930 (approx 17% drop). So although the reported speed is higher (although still not 2666MHz), it must be dual-channel memory access that disappears.

With just the 2 x 16GB (Corsair Vengeance 2666MHz) the system reports 2667MHz memory speed and multi-core Geekbench goes to its highest figure of 8900.

What channels should they be in if it's just the 2 x16 ? 1&3 or 2&4 ? does it matter?

 

[Fred Zed]

I bought 2x16GB Crucial CT2K16G4S266M initially meant for a 2019 iMac. I swapped the iMac for the i7 2020 version since it was released during my return period.

Sadly the RAM runs at 2133MHz on the 2020 iMac when running together with the original Apple RAM Hynix HMA851S6DJR6N. They ran on the expected speed on the 2019 iMac though. Let me know if you have any better luck @DrRadon.

Is there a free version of Geekbench or do you have to buy a license @Limeybastid?

I used the free version to check my figures.
In regards to your installation of the memory, did try using the 9to5 Mac method ? That will be probably get your ram clock speed back to normal but remove the dual channel capability like we’ve discovered.

 

[DQ11]

Just installed OWC 32GB and I also get 2133mhz when leaving in the Apple ram. So what is everyone’s final decision who isn’t buying new ram? My assumption is it’s better to have 40gb at 2133 than just the 32GB at 2666 and putting the Apple memory in a drawer. Thoughts?

That will be my situation. I ordered 16gb with it...but I already have sx16 =32GB RAM from OWC that arrived the other day.

Seems like it may be best for now to just leave the 2x16gb but I'm not sure...I've never owned an imac before.

 

[Robejazz]

Indeed. Just to clarify for others on here. My initial Geekbench test figures ( multicore and singlecore )with the stock 8GB RAM was similar to when I installed the additional 32GB Crucial memory using the 9to5 Mac method totaling 40GB.

However, once I removed the stock 8GB and paired the two 16GB crucial memory modules totaling 32GB my Geekbench scores increased significantly.

Looks like I am n the same boat as you - did you do slots 1 and 3 or 2 and 4?? and you left the remaining slots empty?

 

[Fred Zed]

Looks like I am n the same boat as you - did you do slots 1 and 3 or 2 and 4?? and you left the remaining slots empty?

Original slots 2 and 4 are now occupied with just the Crucial 16GB dimms all else empty.

 

[Brookzy]

To clarify what I meant about "batches" - the RAM I am using is all Crucial but bought at different times. They have different part numbers and so are different in some way. They are each just what Crucial was selling at that time. And the 2020 iMac is particular between them.

But putting the respective pairs in Slots 1 + 2 and 3 + 4 (rather than the conventional 1 + 3 and 2 + 4) means they run at 2667 MHz and CPU-Z in Windows is showing dual channel is active, which is good enough for me. And Geekbench is scoring around 9000 in macOS on my i7.

 

[DOUGHNUT]

i have the 3.3ghz 6 core i5 (mid range) set up. similar to the issue you guys have had with mixing 16gb/16gb sticks with stock 4gb/4gb sticks the performance drops in both configurations. I decided to simply set aside the original 4gb sticks and opted for 32gb total memory. i figure i don't use the iMac for anything that requires intensive memory use (i even tried opening all my apps at once and never once did the memory load get close to maxing out the memory and I'd prefer having better performance than additional 8gb of memory (close to 1000 additional points on multicore score in Geekbench). but everyone's preference is different i guess!

 

[Fred Zed]

To clarify what I meant about "batches" - the RAM I am using is all Crucial but bought at different times. They have different part numbers and so are different in some way. They are each just what Crucial was selling at that time. And the 2020 iMac is particular between them.

But putting the respective pairs in Slots 1 + 2 and 3 + 4 (rather than the conventional 1 + 3 and 2 + 4) means they run at 2667 MHz and CPU-Z in Windows is showing dual channel is active, which is good enough for me. And Geekbench is scoring around 9000 in macOS on my i7.

And what was the Geekbench score with just the original 8GB of RAM installed?

 

[Fred Zed]

i have the 3.3ghz 6 core i5 (mid range) set up. similar to the issue you guys have had with mixing 16gb/16gb sticks with stock 4gb/4gb sticks the performance drops in both configurations. I decided to simply set aside the original 4gb sticks and opted for 32gb total memory. i figure i don't use the iMac for anything that requires intensive memory use (i even tried opening all my apps at once and never once did the memory load get close to maxing out the memory and I'd prefer having better performance than additional 8gb of memory (close to 1000 additional points on multicore score in Geekbench). but everyone's preference is different i guess!

Same setup as mine. Same school of thought.

 

[derekg]

Same setup as mine. Same school of thought.

Same config as well and I'm doing the same 16GBx2 install recommended here. One question: what slots should they go?

 

[Fred Zed]

Same config as well and I'm doing the same 16GBx2 install recommended here. One question: what slots should they go?

I posted the pic of slots a few chats further up.

 

[Mr. Warbles]

Hey guys, got a new 8 core iMac coming and 64GB of Samsung RAM sitting here. I’m going to ditch the 8GB of Apple RAM to get the most out of it.

Now I’m thinking of just getting another 64GB just to max it out to 128GB but do you think it will be a noticeable difference for me?

I mainly use my computer for recording and mixing audio, graphic design (Adobe CC), and simple editing in After Effects.

thanks!

 

[Hulip]

I just ordered 4 x 16 from owc. Can anyone confirm that this works with dual channel and gives the right speed? Originally I was going to use 32 with the apple memory making it 40 but same there were problems. I’m hoping this will help. Didn’t want to pay a little more for the 2 x 32 as this is already overkill for me.

 

[DQ11]

I may also order another 16x2 from OWC....Thing that sucks is I ordered 16gb of apple ram thinking it would be fine because past versions were....so I'll have 16gb of useless memory....I'll just stick with the 32gb of OWC and order another 32GB I guess..

Has anybody tried mixing 8x2 Apple + 16x2 OWC yet?...like that setup specifically?

 

[jacklivehere]

Hey guys, got a new 8 core iMac coming and 64GB of Samsung RAM sitting here. I’m going to ditch the 8GB of Apple RAM to get the most out of it.

Now I’m thinking of just getting another 64GB just to max it out to 128GB but do you think it will be a noticeable difference for me?

I mainly use my computer for recording and mixing audio, graphic design (Adobe CC), and simple editing in After Effects.

thanks!

I am in same boat. Got 2x32gb Samsung installed and working great. Though I want to fill other 2 slots, I don't see real valid reason as I couldn't stress memory more than 28GB in my used case.