Gots to be on N2. If you havnt seen that shit, look up Nitrogen cooled over clocking. They use huge copper heat sink towers that they pour liquid N2 into to freeze the shit out of the proc.
BTW, the world reccord last time I checked was on a P4 3.0 stock running 8.2GHZ!
I have to brag a bit too… I got my E8600 up over 5.0GHZ. Lapped the proc and the Xigmatec cooler, with 2 Ultra Kaze 120mms on it. 5.0Ghz on air is sick. It runs daily at 4.1ghz, and has for the last 6 months or so!