It doesnt, 600w is more suited a higher end pc ie SLI. there is a website thats lets u work out ur power needs.
http://www.extreme.outervision.com/psucalculatorlite.jsp
check that site out, its good, i could be wrong, 600w seems too high for me, let us know what it says.
my pc's requirements is 550w pretty much maxed out usage oc'd too, dont forget to take into account the 12v railing rating.