Cobble together two different pairs of 2GB DDR2 memory sticks and chances are the motherboard will mistakenly report only 2.7GB, 3.3GB or 3.7GB of RAM installed... Worse yet, mixing and matching different 2GB memory sets may force you to use lax memory timings, or even to turn down the memory speed. Bummer. It's a good thing that Mushkin has produced this high performance 4GB memory kit... yes, that's FOUR GIGABYTES!