Installing RAM (2x32gb, 2x4gb) in 2020 27" iMac - Slots for best performance, etc

Mac's are very picky and I'm concerned that those Samsung modules are spec'ed out for PC and not an iMac.

Ideally you would be far better off purchasing Mac compatible RAM modules directly from vendors like Crucial or OWC macsales.com that specialize in Apple memory.

FWIW all you need to do, is leave the factory modules installed where they are and install the 2 new modules into the 2 empty slots.

The slots used can make a difference.

https://9to5mac.com/2020/08/09/how-to-upgrade-2020-imac-ram-video-5k-27-inch-128-gb/

"Instead, I found that it’s best to install two like modules in slot 1 and 2, and the other two like modules in slot 3 and 4 for the best performance. Notice how the same memory configured in this arrangements results in the proper 2666MHz (2667) speed rating."

+ o! n the Samsung DIMMS. I just ordered 2 ea. of the 27" iMacs (his and hers) and also ordered OWC (www.macsales.com) RAM. Macsales specializes in Macs, everything they sell has been tested to work with Macs. In addition they provide a lifetime warranty on RAM , have competitive prices and terrific pre and post sales support if needed. Another great vendor is Crucial.com. My recommendation is to cancel your Amazon order and buy from Crucial.com or Macsales.com

Also, many people overthink installing RAM. Simply install the new DIMMS in the empty slots and you are done!

Oe additional thought. You may already know this, but since you bought RAM that may or may not work, be sure to check to ensure that your Mac recognizes the RAM after installing it. To do this, go to the Apple menu, down to About this Mac and click it. Then on the window that opens, click Memory and it will show you what your computer recognizes. Good luck.

Sorry but I don't see anything in the link you posted, that said those modules are Mac compatible.

Don't over think it. Apple already has the factory module installed for optimal performance and all you need to do, is just install the new modules into the 2 empty slots.

Thanks Malcom, I have 2 27" iMacs on the way, they should arrive September 1-9. The delay is they are custom configurations. I also have 32 GB of OWC RAM on the way too. I will install the base 4 GB of RAM in slots 1 & 2 and the 16 GB DIMMS in slots 3 & 4. Once I have I'll test it out.

By the way the configuration I bought for each of the computers was

Customize your 27‑inch iMac with Retina 5K display

• Standard glass
• 3.6GHz 10-core 10th-generation Intel Core i9 processor, Turbo Boost up to 5.0GHz
• 8GB 2666MHz DDR4 memory
• Radeon Pro 5500 XT with 8GB of GDDR6 memory
• 2TB SSD storage
• Gigabit Ethernet
• Magic Trackpad 2
• Magic Keyboard - US English

No.