I can get mine to 280 but I'm only running a 3000 rpm fan...
I couldn't overclock properly until I went into the bios to the game thing and set it to:
Game Accellerator: Auto
Refresh Cycle Time: Normal
Read Delay: Auto
Read Delay Adjust: Disabled
Command per Clock: Disabled
I also updated to the newest bios. I also got crazy and removed the heat spreader off my p4 2.4 c 800 mhz and now it runs much cooler and overclocks higher...I'm using a thermalright slk-900 copper heatsink which works perfect with the heatspreader off...
I'm currently running 3.3 stable...easily can do 3.4...I know it wants to go higher....I think my ram is the limiting factor...although it's generic samsung chip ddr 333 ram, it overclocks from 166 to about 230 at 2.8 volts (2.5 3 3 7) with vantech copper heat spreaders on the ram....
anyways, two bits worth...