Generally speaking, if you can afford it, your Operating System will run faster with the maximum amount of memory that your motherboard will hold. For your system I am assuming 32GB or 4x8Gb modules. Although depending on how much memory the applications you are running require, after a certain amount you get some diminishing returns the higher you go. If your budget dictates less, for example 16Gb, then your "two-channel" memory controller will access two 8GB sticks more efficiently than four 4GB sticks. Each memory channel controller can access a single module at a time. Think of them as two running in parallel. The hardware will not be able to access three or four sticks simultaneously, but it will still be on the order of a...