EDITED:
Consult this list:
http://www.tomshardware.com/forum/id-1804779/power-supply-unit-tier-list.html .
PSUs are not created equal, there is no regulating body that requires the PSU to be tested to ensure that it outputs what is on the sticker. A cheap psu is like a cheap car amp for less then $100 claiming to output 1600watts.
When a PSU gets 80+ certified then the psu is tested to ensure its output, and that it can do it at any level of efficiency. The 80+ ranking means that it can provide 50% load with no more then 20% loss and that it can provide 100% of stated load. Now this rating alone does not make it a quality psu, a quality unit is designed to work for years and has plenty of over/under voltage/current/temperature protections built into it. Raidmax PSUs have 80+ rating but the company just builds them to pass the test with no regards to system stability, thus they have earned the reputation name of "motherboard killer".
Many brands have both good and bad units. The only real constant safe bets is anything 80+ bronze or better from Atnec, XFX, or Seasonic. There are many other good PSUs out there by EVGA, Corsair, Rosewill etc but you will want to consult the list linked previously.
Best rule of thumb for PCs or anything else for that matter: Don't go cheap on the part that can destroy everything else.