A 6790 is a little faster due to the 256 bit memory bus, but its not worlds faster or anything. Either card will handle some games fine at 1080P, though the ideal gaming res for a 6770 for sure is something around 1440x900. It will just depend on the game and eye candy settings. You wont be able to do Metro 2033 though maxed out at that 1080p on those cards though. You would have to have at least two 6770 cards running in Crossfire, as Metro is a card crusher. If you really want to know more, you probably should google for HD 6770 and 6790 reviews.