iMac (Retina 5K, 27-inch, 2017 RAM Upgrade Best Practice
The base system has 2 x 4GB memory modules installed. Does it make any difference which slot the modules are in, and which modules should/must match in size? Does it make any difference whether the 4GB or 16GB are in the original slots?
iMac 27" 5K, macOS 10.14