[H] Power Supply Goodness?

[Anthony Q. Martin]

How do you tell if a power supply is gone bad?  I bought this Antec Neo 
Power 650 Blue in September 2007. I can't see that I need more watts. It 
has 3 12V rails at 19A each, with a 5 year warranty.  I have no real 
indication that this PS is the problem in my system, though.  By the 
numbers I don't think I need a new one.