I am a three-time member of the 4Ghz club All of those OCs (Pentium 4 4.2Ghz, Core i7 920 at 4.2Ghz, Q9650 at 4Ghz) were on air. I just ordered (Last sat, waiting for the order from Sidewinder Computers to be processed) a massive WC setup for my i7 975 (MCR320+MCR220+MCP655+1/2" Tygon tubing as the basis), with the goal to hit 4.5Ghz. I got the thing to POST at 4.7Ghz before, but at 1.4v the temps on the D0 Bloomfield are too high for any air cooler. Hmm. Drop me a PM with the pricing for the pump, I might be interested. Just take the shipping into account (I am in Israel).