2020 27" iMac. No Start after Ram upgrade

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Level 1

4 points

2020 27" iMac. No Start after Ram upgrade

I am asking this again because everything I find involves older models or Other Ram Modules and does not seem to address the newest iMac or my Ram. Everyone says don’t use Samsung and buy OWC. I did buy OWC and am having the same problem. I have 2020 iMac running OS 11.6.

I just received my 27” iMac and wanted to upgrade the 8 gigs of ram with 2 16gig and the original 2 4s. I accidentally purchased 2 pairs of 16 from OWC/MacSales. (32.0GB (2x 16GB) OWC 2666MHz DDR4 PC4-21300 260-Pin SO-DIMM Memory Upgrade Kit.) so I decided to just go for the 64gig instead of 40 and pull the original 8. Now the iMac won’t power on. No fan or anything. I held the power button for an extended time, Nothing. I waited for a minute or two after pushing the power, Nothing. I pulled the 4 16s and re-installed the original 4s in 1 and 3 slots and it turned on after about 15 or 30 sec. I repeated all this 3 times with same results. What am I Missing. Thanks.

Posted on Nov 11, 2021 5:52 PM

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Answer 1

Top-ranking reply

den.thed

Level 10

91,342 points

Nov 12, 2021 9:33 AM in response to WmasVideo

Keep in mind that the new modules may have slightly thicker blades than original modules and may require more force to fully seat in the slots, especially in the previously unused slots.

I would try this,

Install the original 4GB modules in their original place and two 16GB modules in the empty slots. (test 40GB)
Then remove the original 4GB modules and replace then with the other two 16GB modules. (test 64GB)
If that doesn't work, I would do a test with one 4GB module and three 16GB modules. (test 52GB)

If 64GB configuration does not work, then I would reach out to OWC Support for assistants.

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Answer 2

Jack-19

Level 8

46,242 points

Nov 11, 2021 6:08 PM in response to WmasVideo

Welcome to the Apple Support Communities.

OWC RAM in iMac (27-inch, Mid 2020) has issues. In most other scenarios, OWC and Crucial RAM are the the only recommended Mac RAM vendors, but in this case, only Crucial works well.

Cheers,

Jack

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