what 500w power supply? You can have anything from that 550w psu with 10a on the +12v rails, or a corsair hx 520 with 40 amps. Not to mention, there's the quality issue.
There are MANY, many better choices for cheaper. Try the Xclio Goodpower 500w, which uses the same guts as the antec but with a fan that doesn't ramp down, which is the key to long life in the fuhjyyu capacitors in them, the Enhance ENS-5150, which is a high quality 80+ certified silent power supply (same guts as silverstone 500w EF +), and the Corsair HX 520, which is one of the best picks. 40 amps, silent, modular, and high quality.