Mixing RAM Brands on Latest Intel iMac

[FRVRandAFTR]

Hi kind tech enthusiast.

I had a friend as if it is slowing his latest get Intel iMac down by having 2x 16GB Apple official RAM and 1x 32 Crucial RAM upgrade all in the system at the same time. He used Crucial's tool to ensure it was right but his mismatch combo of Apple Branded/ Crucial (48GB total) is doing more harm than good? For what it's worth, he's using BootCamp a lot if it matters but with the way his machine was BTO minus the RAM, he thinks 48GB RAM should be blazing for his three background Safari tabs (if that) and MAYBE light LightRoom work.

Thanks!

 

[Sheepish-Lord]

If all the specs are the same then brand consistency isn’t really necessary. Personally I would swap in all new memory at the same time for piece of mind knowing the life expectancy will be the same especially if the ram is cheap.

 

[Nermal]

I put two different brands in mine and it refused to run at 2667 MHz. There's a huge thread about RAM issues with this machine.

 

[velocityg4]

The main problem with mixing is with computers using XMP profiles. Which overclocks the memory using settings specified by the memory manufacturer. You'll just be using certified JEDEC timing and speeds. So, as long as the new memory supports the standard timing and speeds used by the Mac. There shouldn't be an issue.

 

[wilberforce]

Hi kind tech enthusiast.

I had a friend as if it is slowing his latest get Intel iMac down by having 2x 16GB Apple official RAM and 1x 32 Crucial RAM upgrade all in the system at the same time. He used Crucial's tool to ensure it was right but his mismatch combo of Apple Branded/ Crucial (48GB total) is doing more harm than good? For what it's worth, he's using BootCamp a lot if it matters but with the way his machine was BTO minus the RAM, he thinks 48GB RAM should be blazing for his three background Safari tabs (if that) and MAYBE light LightRoom work.

Thanks!

Whatever you do, make sure you have the same amount of RAM in Channel A as in Channel B, otherwise the mismatched portion will run in single channel mode, which is effectively half speed. This is why you should upgrade in matched pairs, e.g., use 2x16 rather than 1x32

 

[gilby101]

Taking "Latest Intel iMac" to mean the 2020 iMac, I have just added this to the other new thread on this topic:

Two long threads from 3 years ago:

Memory upgrade troubleshooting in 2020 27-inch iMacs

Hi all! First post on this site. I received my 2020 27" iMac (tier 3 stock configuration) yesterday and have been using it happily since. Today I received some Crucial memory (CT2K8G4S266M aka 2 sticks of 8GB 2666) and I installed it in the two slots that were occupied by the Apple memory, which...

forums.macrumors.com

Memory upgrade compatibility list for iMac 2019-2020

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...

forums.macrumors.com

From AskDifferent:

iMac Retina 5K 27-inch 2020 RAM Upgrade comatibility

I would like to update my RAM from 40 Gb to 96 Gb I have a iMac Retina 5K 27-inch 2020 running BigSur 11.6 with the following RAM: Slot1: Kingston KCP426SD8/16 16GB Slot2: Micron 4ATF51264HZ-2G6E3...

apple.stackexchange.com

And Apple:
https://support.apple.com/en-us/HT201191 which includes this for 2020 iMac: "For optimal memory performance, DIMMs should be the same capacity, speed, and vendor." But this is not a requirement for the similar 2019 iMac.

So for the 2020 iMac do yourself a favour and get 2 or 4 identical DIMMs. Don't mix.

 

[PBG4 Dude]

The main problem with mixing is with computers using XMP profiles. Which overclocks the memory using settings specified by the memory manufacturer. You'll just be using certified JEDEC timing and speeds. So, as long as the new memory supports the standard timing and speeds used by the Mac. There shouldn't be an issue.

It is an issue with the 2020 iMacs which is why there are huge threads (noted in previous posts in this thread) where the issue was dissected and solutions / workarounds determined.