dokk2, it's not the voltage that counts. The voltage will always be 12 volts. It's the power (voltage X current) that counts.
You mean the maximum current. The voltage will always be 12 volts.
My OC'd Q6600 pulls 9.5 amps at 3.6 GHz as measured with a lab calibrated clamp-on ammeter. I cannot see any current AMD chip pulling much more.
Do you need 8 pin connector? No. For your system, the 4 pin connector will be adequate. 8 pin, however, would be better.