When choosing a power supply, look at the amps supplied by the 12 volt rail, not the volts supplied by the 12 volt rail

We know what that is. Some of the shadier power supply companies declare the total watts pulled from the wall, not the usable watts supplied to the computer. What someone, like Antec, calls a 500watt psu that supplies 40 amps, another company may call 750 watts because that's what is being pulled from the wall. ~30% of power is lost and converted to heat, so it shouldn't be counted.