Possible- yes. Adviseible, not so much. Most of the eMac G4's have the same problems as the iMac G3's they have BAD cooling systems... By overclocking it you are risking destorying it because you stayed up late to write a history essay. You probably wouldn't need any watercooling, a fan would be good, but it will be tosty if you don't give it good ventilation... Check out the iMac
overclocking to get a good idea of what in intales.