I have a slightly older motherboard (ASUS A8N32-SLI) and 2 EVGA 8800 GTS 512MB cards. I know the cards I have support PCIe 2.0, but the mobo only supports 1.0[a?] -- on the plus side, though, the mobo does support full dual x16/x16 in SLI.
So, I'm looking to possibly upgrade my mobo/cpu/ram from 939/Athlon X2/DDR to AM2+/Phenom/DDR2. However, I've discovered in my research that most reasonably-priced mobos with 2 PCIe 2.0 x16 slots can only run dual x8/x8 in SLI.
My question is this: from a purely graphics-oriented perspective (ignore the boost in cpu and ram from a new mobo), which is better - PCIe 2.0 x8/x8 or PCIe 1.0 x16/x16?
Neither, PCI-E 2.0 is twice as fast as PCI-E 1.0/1.0a so you`ll have the same bandwidth with either setup.
Unless you plan on some very powerful upgrades to the graphics (a pair of GTX285 or more) you`ll not need more bandwidth than is already available.
Yup, the bandwidth from each is the same, the only reason the PCI 2.0 system would likely perform better are either cpu upgrade, ram upgrade, or using a single card a few years from now (as 16x PCI 2.0 is 2x as fast as 1.1).