Increasing Memory of 2019 iMac Running 3GHz Processor

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Level 1

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Increasing Memory of 2019 iMac Running 3GHz Processor

I am still running OS Mojave but may try to install Sonoma but first want to increase the memory.

I have 4 memory slots but only 2 are occupied. They each have a 4GB memory card. I understand that a 3GHz processor only allows a maximum of 32GB of memory to be installed instead of 64GB. If so I am intending to increase memory to 16GB and later to 32GB.

Do I have to remove the 2 x 4GB cards before I install a kit of 2 x 8GB cards or can they remain to give 24GB memory? In the future I may increase the memory by removing the 4GB cards and replace them with another 2 x 8GB kit.

iMac 27″, macOS 10.14

Posted on Jan 23, 2024 2:32 AM

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Answer 1

Top-ranking reply

VikingOSX

Level 10

128,958 points

Jan 23, 2024 4:14 AM in response to ajogger

You can just add compatible memory cards to the existing RAM. Keyword is compatible as Macs are really fussy about the RAM. I purchased my RAM directly from OWC or Crucial (links to RAM for your 27-inch 2019 iMac) for my 2020 Core i7 iMac, I added 2x16GB cards to the existing 8 GB (2x4 GB) that came with the iMac. Has continued to work like a charm with 40GB RAM for over two years now.

It is important that you seat the RAM correctly, or you will get a series of three beeps when you attempt to boot the iMac.

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Answer 2

ajogger Author

Level 1

11 points

Jan 23, 2024 7:02 AM in response to VikingOSX

Hi VikingOSX

Many thanks for your useful reply. I didn't include that mine is a late 2019 Retina 5K Core i5 iMac rather than i7 that your is. But having carefully checked Crucial's web site I can see that they offer both 16 GB and 32GB kits for my machine. But the only thing that I don't quite understand is that when I look at my system "About this Mac - System Report - Memory it shows that the two slots that I have occupied contain 4GB DDR4 2667 MHz cards not 2666 MHz cards that Crucial are offering. Should I be concerned please.

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Answer 3

stedman1

Level 10

267,218 points

Jan 23, 2024 7:05 AM in response to ajogger

The discrepancy between 2666/2667 is not an issue. It is simply the preference of some to use rounding for the speeds. The actual speed is 2666.66 MhZ.

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