"I just wanted to get a cheap case" mmmmmmm the case in my opinion is second only to the power supply when building a pc as after all the power supply supplies all your expensive components with power and the case holds them and keeps them cool. Try
http://www.lian-li.com next time. But anyway thats my little rant over
Yeah it just trial and error for the cpu voltage. Just keep lowering it and starting the pc, eventually windows wont boot and you know youv gone to far down. Windows will then restart and you go back into the bios and increase it again.
Generally if you got down to lets say 1.2000 volts and it didnt boot a setting of 1.2250 would be stable. Oh and cheers for the rep.