I OC'd the e6600 on a asus p5b-delux to 3000 mhz on stock cooling with no problems. It ran at around 48Cat idle to around 55mhz at load. I couldnt reach 3200 with the stock fan stable, altho I heard it was done. For comparison, I have sine upgraded to a Tuniq Tower 120 hsf and got same temperatures at 3600 mhz. So yea its very possible to OC, as yas said you will be limited.