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iMac 2019 27 - Mixing RAM from the same Mfr.
- Thread starter kretek
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Mfr doesn't matter.
All that matters is the RAM spec is correct, in your case: 2666MHz DDR4 SO-DIMM (aka PC4-21300).
Assuming the RAM spec is correct, replacing one 4GB stick with one 8GB stick is "ok" in that it will run, but not optimally, because the amount of RAM in Channel A will not match the amount of RAM in Channel B. This will reduce the effective memory transfer speed because it will not be running full dual channel. In real usage, you may not notice this reduction in memory transfer speed.
Ideally you should replace two 4GB sticks with two 8GB sticks, so that each channel has the same amount of RAM. This requires ordering the slots: 8-4-8-4 (not 8-8-4-4)
All that matters is the RAM spec is correct, in your case: 2666MHz DDR4 SO-DIMM (aka PC4-21300).
Assuming the RAM spec is correct, replacing one 4GB stick with one 8GB stick is "ok" in that it will run, but not optimally, because the amount of RAM in Channel A will not match the amount of RAM in Channel B. This will reduce the effective memory transfer speed because it will not be running full dual channel. In real usage, you may not notice this reduction in memory transfer speed.
Ideally you should replace two 4GB sticks with two 8GB sticks, so that each channel has the same amount of RAM. This requires ordering the slots: 8-4-8-4 (not 8-8-4-4)
Last edited:
Understood, thanks for the reply
Ram prices have shot up significantly in the last 4 months. I was trying to skimp just going with one stick I found at a good price.
Ram prices have shot up significantly in the last 4 months. I was trying to skimp just going with one stick I found at a good price.
