Today I got a Radeon 7770 (I wanted a 7850 but whatever). I have almost enough money to buy a second card and Crossfire it. My board however is only x16/x4. I know that when Crossfired the 7770 performs pretty well. What kind of performance hit would I see by crossfiring the two cards on this board? I don't care about micro stuttering or any bottleneck (I will probably get an FX 8350 down the road) just the performance I would see. Can I do this? Thanks.