You could potentially run it on a 1600 W Power supply as long as it runs at least 90% efficiency. At 80% you would only be producing ~1280W and the S9 needs 1372W. At 90% efficiency you are around 1440W. The EVGA SuperNOVA 1600 Gold runs at 90% and the Titanium at 94%. Higher efficiency power supplies cost more, but you will make up the cost in no time since higher efficiency means the power supply uses less power. They are also safer and should last longer since they don't produce as much heat. In this case you can get away with a 14 gauge power cord as long as you don't consume more than 15 amps on this one circuit and you don't plug anything else but the miner into it.