"We decided to take a generic 500 W power supply and test it using the same methodology we use for "branded" units. The idea behind this review is to be as much educational as possible and answer a few very important questions: how much power a generic power supply can really deliver? What are the differences between a generic power supply and a "branded" unit? Is there any danger for my equipment to use a generic power supply? Why generic units cost so little? Read on and see our findings."

 

Hardware Secrets actually rip open a 500W PSU in this article to reveal the internals, which really helps you understand how they work.