The following are the power supply hardware requirements:
Geforce GTX 470
Minimum of a 550 Watt power supply.with a combined +12 Volt current rating of 38 Amps
Two available 6-pin PCI-E power connectors
Geforce GTX 480
Minimum of a 600 Watt power supply with a combined +12 Volt current rating of 42 Amps
An available 6-pin PCI-E power connector and an available 8 pin PCI-E power connector