I swear by Enermax for PSUs, popular and proven brand. My computer is on 24/7 and has been running great since I changed power supplies 1.5 years ago.

The power rating of cheaper no-name power supplies can not be reliably compared with that of proper brands.

My previous no name power supply claimed to be 460W but was a lot weaker than the 400W Enermax I now use.