They don't have to be the same, but as with a lot of computer issues, matching drives can keep you form having compatibility issues. I'm running the raid 0 on one box more as an experiment to see if there is any diff in performance and as mp33 stated, there is'nt much. Load times are a little faster due to faster read speed. Photo/video editing is faster, but for games and everything else, I can't notice a diff. My box with a single hd is faster because the whole system is faster( cpu, ram, mobo, vid card) I think it's been said enough times now that a good vid card is usually the choke point of a gaming rig if that's what you're after. Put a great vid card in a so so comp and it will perform the same or better than a super fast setup with a so so vid card.