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 part numbers (compatibility verified and confirmed on manufacturer's website):
See the 2666 MT/s modules in Crucial Memory for Mac Systems
Compatible Crucial part numbers (Tested from Forum users):
Crucial CT2K32G4SFD8266 64GB Kit (32GB x2)
Compatible Kingston part numbers (compatibility verified and confirmed on manufacturer's website):
Compatible OWC part numbers (compatibility verified and confirmed on manufacturer's website):
Compatible Samsung part numbers (compatibility cannot be verified on manufacturer's website):
Compatible SK Hynix part numbers (compatibility cannot be verified on manufacturer's website):
iMac 2019-2020 needs :
See Installation instructions upon receiving your RAM module(s).
Please note that many people on this forum experienced problems when mixing genuine Apple RAM with third party RAM. It might not be possible to mix your genuine Apple RAM with the modules listed above without impacting stability and performance. Memory configuration with 2 or 4 memory modules coming from the same third party vendor is strongly recommended.
For troubleshooting RAM, please refer to this thread Memory upgrade troubleshooting in 2020 27-inch iMacs
Rules of thumb :
Memory upgrade compatibility list for iMac 2019-2020
Compatible Crucial part numbers (compatibility verified and confirmed on manufacturer's website):
Part number | Capacity | Amazon US | Amazon Canada | Amazon UK |
CT8G4S266M | 1 x 8 GB | Buy now | Buy now | Buy now |
CT16G4S266M | 1 x 16 GB | Buy now | Buy now | Buy now |
CT32G4S266M | 1 x 32 GB | N/A | Buy now | Buy now |
CT2K8G4S266M | 2 x 8 GB | Buy now | Buy now | Buy now |
CT2K16G4S266M | 2 x 16 GB | Buy Now | Buy now | Buy now |
CT2K32G4S266M | 2 x 32 GB | N/A | Buy now | Buy now |
See the 2666 MT/s modules in Crucial Memory for Mac Systems
Compatible Crucial part numbers (Tested from Forum users):
Crucial CT2K32G4SFD8266 64GB Kit (32GB x2)
Compatible Kingston part numbers (compatibility verified and confirmed on manufacturer's website):
Part number | Capacity | Amazon US | Amazon Canada | Amazon UK |
KCP426SS6/4 | 1 x 4 GB | Buy now | Buy now | Buy now |
KCP426SS8/8 | 1 x 8 GB | Buy now | Buy now | Buy now |
KCP426SS8/16 | 1 x 16 GB | N/A | N/A | N/A |
KCP426SD8/16 | 1 x 16 GB | Buy now | Buy now | Buy now |
KCP426SD8/32 | 1 x 32 GB | N/A | Buy now | Buy now |
Compatible OWC part numbers (compatibility verified and confirmed on manufacturer's website):
Part number | Capacity | Amazon US | Amazon Canada | Amazon UK |
2666DDR4S08G | 1 x 8 GB | Buy now | Buy now | N/A |
2666DDR4S16G | 1 x 16 GB | Buy now | Buy now | Buy now |
2666DDR4S32G | 1 x 32 GB | Buy now | Buy now | Buy now |
2666DDR4S16P | 2 x 8 GB | Buy now | Buy now | Buy now |
2666DDR4S32S | 4 x 8 GB | N/A | Buy now | Buy now |
2666DDR4S32P | 2 x 16 GB | N/A | Buy now | Buy now |
2666DDR4S64S | 4 x 16 GB | Buy now | Buy now | Buy now |
2666DDR4S64P | 2 x 32 GB | Buy now | Buy now | N/A |
2666DR4S128S | 4 x 32 GB | N/A | N/A | N/A |
Compatible Samsung part numbers (compatibility cannot be verified on manufacturer's website):
Part number | Capacity | Amazon US | Amazon Canada | Amazon UK |
M471A5244CB0-CTD | 1 x 4 GB | N/A | N/A | Buy now |
M471A1K43CB1-CTD | 1 x 8 GB | Buy now | Buy now | Buy now |
M471A1K43DB1-CTD | 1 x 8 GB | N/A | N/A | N/A |
M471A2K43CB1-CTD | 1 x 16 GB | Buy nowBuy now | N/A | Buy now |
M471A2K43DB1-CTD | 1 x 16 GB | N/A | N/A | N/A |
M471A4G43MB1-CTD | 1 x 32 GB | Buy now | Buy now | Buy now |
Compatible SK Hynix part numbers (compatibility cannot be verified on manufacturer's website):
- HMA81GS6CJR8N-VK *
- HMA851S6DJR6N-VK (original Apple RAM installed in 2020 iMac)
iMac 2019-2020 needs :
- PC4-21333
- Unbuffered
- Nonparity
- 260-pin DR (Dual Ranked) or SR (Single Ranked)
- 2666MHz
- CL19
- 1.2v
- Source : Install memory in an iMac.
See Installation instructions upon receiving your RAM module(s).
Please note that many people on this forum experienced problems when mixing genuine Apple RAM with third party RAM. It might not be possible to mix your genuine Apple RAM with the modules listed above without impacting stability and performance. Memory configuration with 2 or 4 memory modules coming from the same third party vendor is strongly recommended.
For troubleshooting RAM, please refer to this thread Memory upgrade troubleshooting in 2020 27-inch iMacs
Rules of thumb :
- Do not mix RAM modules with different capacity/speed/manufacturer. A OWC memory kit with Hynix ICs won't work with an OWC memory kit with Micron ICs, even if they are "For Mac", with the same speed, timings, comes from the same manufacturer, and other specs.
- If you chose to upgrade to, for example, 2x32 GB, and have 2 memory slots free for future upgrade, chose Crucial RAM. It's the only RAM brand which has a unique ICs manufacturer which is Micron. Kingston usually have a locked BOM for ValueRAM Server RAM, but I can't find the same information for Mac RAM. Crucial is the only 100% certified compatible RAM and guarantee that it will work in the future when adding a second kit.
- No experiment show that mixing Apple stock RAM with aftermarket RAM listed above is correctly operating at full speed and in dual channel. Don't mix Apple RAM with aftermarket RAM.
- Memory must be installed in slot 1-3 and 2-4 when in kit of 2 SODIMM modules. If all 4 SODIMM are populated, make sure all ICs are coming from the same manufacturer. If not, dual channel is lost.
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