Hey mang. My theory on this. I've never run SLI but my theory would be... Why go THROUGH two cards, when you could have it in one. I know its like doubling the power or whatever but, you have the same amount I would assume. So if the same memory space is there, then I wouldn't want to travel through ONE to get to the other for full power when you could just have one. Hey, that's just my theory though...