SLI? Gimmick or performance?
I'd like to hear your opinions on whether you think SLI is a gimmick or a real performance gain.
I think it's a gimmick. Here's why.
Ok so one video card does half the pixels and the other does the other half. Big deal. How does the other video card know which pixels to render? We are talking about 3D here. You CANNOT know where the pixels will be until you transform the vertices into screen space. Thus you must still send your vertices to one card for processing. That card will transform them and then send the one's that are not in it's range of pixels to the next card. Big hair deal. We already know that one video card can blit more pixels and render more tri's in one frame than there are available in any one screen mode. So fill rate is no longer the problem.
The real bottleneck is getting the vertices to the card, not with the card drawing the pixels to the screen.
So how does card A know what to send card B w/o first transforming all vertices into screen space?? Now if they found a way to have the cards know which vertices will fall where in screen space, then of course there will be a gain if both card's are transforming vertices.
But how would you do this? You cannot know which vertices will resolve to which pixels until you do some type of transformation on them.
I say gimmick.