You need 2 cards that are the same such as my 2 512MB BFG GeForce 7950GTs.
Sell your GeForce 7950GX2, then get another 7950GT and pocket the rest and you'll be SLIing and it'll be faster, too.
There isn't a game out there that 2 512MB 7950GTs won't play at 1600x1200 with everything turned on to the max.
