Working on a build that I'd like to be at least somewhat future-proof. The only piece I already have is the HD7970, which I'm essentially building the whole system around. I already know that PCI-e 3.0 will only give me about a 1% increase in performance over PCI-e 2.0 as far as my single HD7970 goes. But down the road when my 7970 is starting to get a little outdated, I plan on CrossFiring it. So what I'm wondering is whether PCI-e 3.0 has a more detectable advantage over 2.0 when running dual graphics cards. Not interested in 3 or 4 cards, just 2. I could save a good deal of money getting a MB and CPU that use PCI-e 2.0, I just don't wanna be kicking myself down the road.