I'm trying to determine if my power supply is sufficient for my new GTX660 card. I'm concerned that I don't have enough AMPs on my 12V rail. Card calls for 24, but it looks like I only have 22? I have no other other devices plugged into the PSU besides my 2 case fans.
For a system using a single GeForce GTX 660 (non-Ti) graphics card NVIDIA specifies a minimum of a 450 Watt or greater system power supply that has a maximum combined +12 Volt continuous current rating of 24 Amps or greater and that has at least one 6-pin PCI Express supplementary power connector.
Total Power Supply Wattage is NOT the crucial factor in power supply selection!!!Sufficient Total Combined Continuous Power/Current Available on the +12V Rail(s) rated at 45°C - 50°C ambient temperature, is the most critical factor.
Overclocking of the CPU and/or GPU(s) may require an additional increase to the maximum combined +12 Volt continuous current ratings, recommended above, to meet the increase in power required for the overclock. The additional amount required will depend on the magnitude of the overclock being attempted.
The Antec EarthWatts EA-500D Green power supply unit, with its maximum combined +12 Volt continuous current rating of 37 Amps and with one 6-pin and one (6+2)-pin PCI Express supplementary power connectors, is more than sufficient to power your system configuration with a single GeForce GTX 660 (non-Ti) graphics card.