depends on the spec of your mobo... before getting those i'd max out your exisiting ram, i just bought the 4gb sticks, and i'd like to say they run a dream but i can't... ive got a "Asrock 4CoreDual-SATA2" which is a good middle step, but can only hold 2gb of ram, though this information is not available on the manufactures website.. so a little annoyed.. so ive only got one stick in.. but nobodies fault except the manufacturer being economical with the truth...