i found this
online power supply calculator last year, and it is what guided me towards the PC Power & Cooling Silencer 750 that i am using now. now according to that calculator, i could add another 8800gtx for SLI, and replace my socket 939 with a new LGA 775 mobo and a nice new yorkfield quad. so is this calculator accurate? because according to it, i can keep using my Silencer 750 quad for a new SLI rig with a pretty high end quad core CPU.