I'll contact AMD to confirm if games are supported in 4 screens for 3D surround. I know AMD can support more than 3 screens but not sure if it can support 4 screens when gaming as surround.
you could do this, but you wouldnt be able to get as up to date motherboard, this one is top of the range, pci 3.0 and will support btoh the gpu's at 16x16x, whereas is you went with an amd build, you wouldnt be able to get the pci 3.0 which is needed for running dual 680/7970/50's, well its not fully needed, but 680/7000 series were designed for pci 3.0, one card will run fine on pci 2.0, however two cards on a pci 2.0 may bottleneck. If that makes any sense.