At first I was looking at Asrock z77 pro4, but since I heard extreme4 is better for overclocking I went with ex4. Than I was checking out prices and saw that extreme6 really close to extreme4 in price, so what the hell.. What I want to know is if ex6 is same as ex4 in performance (no downsides of course) and can it run 2 GPU's at x16 3.0 speed? Or is is the difference between 2x 16 and 2x 8 too small to bo bothered with?
And is 7970 worth extra money over 7950? I can spend extra money on GPU, but I don't want to if it's not worth it. (Was looking at 670 also, but I went with 3GB memory the 7970 have).