Question 1

I have 16G installed in in my 2017 27" retina iMac.  If I purchase a 32G kit and install it with the 16G (giving me a total of 48G) will this work?

Accepted Answer

It should. The max RAM for that model is 64GB, and I've mixed different sized RAM sticks in the same model iMac before without a problem. Just try to make sure you get RAM with the same speed and timings.

Question 2

Have the 2017 27" iMac 3.5 GHz with 8GB (4x2) installed and wanting to increase it.  According to Apple specs it says the memory is 3.5GHz
8GB (two 4GB) of 2400MHz DDR4 memory; four SO-DIMM slots, user accessible, Configurable to 16GB, 32GB, or 64GB.  If I add 32 GB to the 8 will it only use 32GB?

Accepted Answer

You can only use 4GB, 8GB, or 16GB DIMMs, you cannot use a single 32GB DIMM. You have two empty slots, so if you want to add to what you already have you can add 2x4GB, 2x8GB, or 2x16GB. I had the same as you, two 4GB DIMMs for 8GB. Then I added 2x16GB DIMMs for a total of 40GB. That’s been plenty of memory for me.

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