Geforce 7600GS Volt recomendations?

Yes I have a GIGabyte Mobo and in the bios there is an option to up the volts for my video card. And i was wondering how many volts i should up it t0 because i want to give it more power to oc higher if thats possible? anyway i cant get my core past 500 because when i got to 510 it totaly freezes in aquamark. The stock core is 450 so im only getting 50mhz. my memmory speed wont go past 990 its stock at 800 and it even crashes at 990. When i oveclcok all of that i go in aquamark 3 from 55,000 to 60,000 and thats adding another 200mh to my cpu.. so im stuck until you tell me other things i could do to raise that score.. also i am gonna get 2 gigs soon.. so maybe that will help. until then what should i do?