It looks like I've hit a wall, even at 1.52v I can't get the bus speed to get stable over 240Mhz. Temps are at 68-70C so I've still got quite a headroom. Anyone with more experience OCing P4s could lend a hand? edit: It passes Prime95 for some reason. Cinebench also completes without errors, it's just Intel Burn Test that fails... I guess I'll keep going edit2: nah, at 245 cinebench locks and at 250 it doesn't even boot. I think this chip is good for 240FSB only.