so, by PCI 3 support you mean at least a sandy or ivy? Amd didnt supported PCIe 3 last year i think now I dont know... anyway I've read people telling that even if it was possible to use a pcie16x card in a 1x slot it wouldn't matter for the outcome. You have any sources or any place I could read abou it?
edit: so ive been reading and what i read earlier was just dumb people, pice3 have actually a much bigger bandwitch than the pcie2 and it can increase the overrall graphic performance