Or a good 380 or 430W.
It's amazing that people don't realize this.
"Minimum of a 400 Watt power supply.
(Minimum recommended power supply with +12 Volt current rating of 26 Amp Amps.)
Minimum 450 Watt for SLI mode system.
(Minimum recommended power supply with +12 Volt current rating of 28 Amp Amps.)
An available 6 pin PCI-E power connector (hard drive power dongle to PCI-E 6 pin adapter included with card)"http://www.newegg.com/Product/Product.aspx?Item=N82E16814130379
26 amps for 1 card , 28 amps for 2 should tell everyone something about how bloated the reccomendations are to begin with.
PS to all; OP's choice of power supply can theoretically power SLI with it's 28 amp rating