my to complete builds and not barebone builds are both mATX builds.
they do of course have a few mATX boards with x-fire and sli. (i prefer sli but that's another story...;))
Okay, let's just say that for now, I've ditched the idea of x-firing -- I am getting a 6870, which is a powerful card by itself. I return to my original question: will I see any detrimental effects on performance?