Hello, I've built about half a year ago a 2500K. My hardware is: an asus uAtx p67-pro mobo, a 4870x2 and 4 gb. of HyperX (XMP). The memory is CAS7. Now I want to sink some money in memory and have 2 banks left, but I don't know what to do. Should I get 4 gb. of the same memory or should I get 8 gb. It also has a CAS of 7 but is not XMP. I build this machine to make a fast SFF games/multimediaPC with some room for o/c íng. Could someone give me some advise on this matter? Thanks