The aren't a lot of situations to quad-sli or quadfire.
But there are some that will at least benefit from them:
5760x1080 in 3D Vision
5760x1080 @ 120hz
In very few cases, 5760x1080 may benefit, but it will be rare, and probably cause more issues than help most the time.
That was my point, if you can run 2 690's on 2 x16 slots then 4 680's should run on 4 x8 slots, its the same total amount of bandwidth whatever way you look at it....
Completely agree with bigcyco1 and bystander though, its really only useful as an enthusiast machine, the amount of scaling after 2 cards on typical resolutions is miniscule, if thats the case though you may as well go all out and buy an x79 etc, but I'd still wait for IB-E...
I did hear someone saying that 3 way SLI/CFX helps to reduce micro-stutter anyone know if theres any truth in that? and if so does 4 make it better or worse?