I have a iMac (Retina 5K, 27-inch, 2017) with 8GB internal RAM. I now wish to upgrade my RAM, do I need to duplicate what is onboard already, e.g. 2x4 GB which will give me 16GB in total or can I add 2x8 GB making 24GB in total.
Thanks, hope I have explained it okay
Graham
It is best to only use memory from either Crucial or OWC since Macs are very picky about the RAM they use. Even then, make sure to only get the exact part numbers suggested by using the tools on their respective websites to identify the exact part numbers compatible with your Mac. Buying memory using just the published technical specifications is not enough since there are a lot of other technical specifications that neither Apple nor most memory manufacturers list which are extremely important for compatibility. When Crucial ships the memory, the plastic packaging actually says "Mac Compatible" on it. If it does not say this, then double check that the memory you have received matches the exact part number suggested by Crucial.
It is best to only use memory from either Crucial or OWC since Macs are very picky about the RAM they use. Even then, make sure to only get the exact part numbers suggested by using the tools on their respective websites to identify the exact part numbers compatible with your Mac. Buying memory using just the published technical specifications is not enough since there are a lot of other technical specifications that neither Apple nor most memory manufacturers list which are extremely important for compatibility. When Crucial ships the memory, the plastic packaging actually says "Mac Compatible" on it. If it does not say this, then double check that the memory you have received matches the exact part number suggested by Crucial.
Your explanation was fine. Your iMac can be upgraded up to 64GB. You do not have to duplicate what is installed other than having the correct RAM: 260-pin PC4-19200 (2400 MHz) DDR4 SO-DIMM
How much RAM Memory
