You will need a supply rated at least 384W or 32A on the +12V rail.
Some good suggestions:
XFX Core 550 / XFX Core 550
Antec HCG-520
Seasonic S12II-520
Seasonic S12G-450
This last supply may sound low at 450W, but it is a top quality 80 plus gold rated supply with a +12V rating of 37A.
The EVGA supply suggested above is tier 3. It is not too bad, but not great. On par with the Corsair CX series. EVGA do make some great supplies, but this model isn't one of them.
Much better buys from the same site:
XFX Pro 550W for $55.99
http://www.ncixus.com/products/?sku=59615&promoid=1011
Seasonic S12II-520 for $62.99
http://www.ncixus.com/products/?sku=52173&vpn=SS-520GB&manufacture=Seasonic%20Electronics&promoid=1011
The XFX supply is manufactured by Seasonic. Very good quality, 80 plus bronze and rated at 44A on the +12V rail.
The Seasonic is of course also manufactured by Seasonic. Slightly lower rating at 40A on the +12V rail, but this is still plenty.