I could run you some tests with my sig rig Just name the software.
I dropped the VCCIO and saw about 5c lower temps. I think 5GHz 1.375V is still considered a good overclock on air if I can get some Prime95 results
put it on like medium settings, no aa/af, your default resolution, and then run the same benchmark (some sites use the opening on-rails part of single player with fraps running). do this test for 4.5 ghz, 4.6, ... up to 5.0ghz. Would be really curious to see how the FPS scales on these higher end overclocks.