Though Core 2 Duo is the chip of choice for overclockers these days, as far as raw GHz goes it still doesnt allow for as high a ceiling as that of the previous Pentium IV gen. As such, there happens to be a race for 8GHz in the works. OC Team Italy have been tinkering with some serious cooling on a Pentium 4 631 (3GHz) chip and have already managed a massive clock speed of 7520MHz.
I've a feeling it wont be long at all before the 8GHz milestone is reached.
Finally we tested our golden 631 with ln2 cooling;unfortunately the motherboard wasn't modded but next time we will set everithing to take the absolute wr on p4 platform
-asus p5b@1,7V (1,6 real voltage with an exagerate drop)
-2x1Gb Cellshock PC8000
-Pc Power&cooling 1kw