the minimum for 6600gt is 300 watt it will work perfect trust me. tigerdirect tells you! the minimum for 6800 is 350watt. but ur good. 6600gt minium is 300watt.. but yes i would also recomend a name brand good 300 watt itleast. i just purchased evga 6600gt from newegg can wait to get it!! lol and i also have a 300 watt psu but it is a nice 300watt its not generic. it puts out plenty of good even amps.