+1 bob
You dont "need" PCIe 3.0, even if you run multiple GTX690/Titan/7970/680. PCIe 2.0 x16 is still able to feed those GPU. PCIe 3.0 could really benefit to incoming newer GPU ( not next gen but maybe in 2 or 3 gen down the road, this mean at least 2 years ). If you run triple or quad GPU, then maybe, PCIe 3.0 could help if your 3rd or 4th GPU fall into a x4 slot. An x4 3.0 perform as a x8 2.0.