My machine came with 16GB RAM. One 8GB card in each bank. I want to add 32GB. Are the factory installed memory cards in primary slots? Should I put the 2 16GB cards in their slots and move the 8GB cards? Does it make a difference?
iMac 27", macOS 10.15
Doesn't really make a differences. Your best bet though, is to just install the new modules in the empty slots.
see > Install memory in an iMac - Apple Support
Mac's are picky, where you buy RAM is a bigger deal.
Memory under Hardware in System Information shows Micron as the RAM mfg. I will purchase directly from Crucial.
Also, why would eshop list 128GB maximum RAM for this machine when Apple lists 64GB?
Because the Apple spec's only go up to their factory RAM configurations and for years OWC macasales.com has tested and sold greater RAM configurations.
2019 27" iMac RAM upgrade.
