Corsair, Seasonic or Enermax
NEVER buy an "affordable" PSU. Particularly a high-power one.
Second both of this and most of what was said by others in this thread...
video example of a bad PSU when stressed @ below what it's rated to provide :
http://www.youtube.com/watch?v=zWt3St_MhSY&feature=player_embedded
there was one that was worse with the whole room going black because of the return current & the room electric security kicking in but I don't find it anymore...
here's a french website (can use google translate) :http://www.pcworld.fr/article/comparatif-de-105-alimentations/lc-power-3-alimentations-resultats/94911/
basically two of 3 LC power died when the load reached 350W while being rated for 550W
the worse being than THE FUCKING POWER SUPPLY SECURITY DID NOT KICK IN !!!!!!!!!!!
which means the rest of your electrical installation suffers from "return current" in those kind of events which could provoke fire or death of other equipment ....