I am talking in general terms. Say you have a graphics card named super graphics 10 and on the card is graphics chip named super 10. Which in general terms would tend to give you the best performance. Two super graphics cards in SLI/Xfire or one single card with two super 10 graphics chips on the board. I am also assuming two the chips on the single card have the same specs as the chip on the SLI cards.
I hope I am explaining my properly lol
I hope I am explaining my properly lol