I'm 100% certain that you can, I've done it before, The only thing I'm not sure of, is if you can use differen't types.. Like, I've done it with an eVGA 7800 GTX KO, and a MSI NX7800 GTX, Now.. Those worked just perfectly for my computer, but if you made one let's say a 7600, I'm not sure if it'll work, it should though.