I agree with xriqn. There is soo much more to a psu than output rating. Protection circuits for a start (over volt, short circuit, etc..), ripple suppression,voltage regulation. Poor ripple suppression to within 50% of within spec (so for 12v rail spec is +/- 120mV) so a ripple of 60mV constantly can reduce lifetime of parts signifigantly. The closer you get to that spec limit, the more it can affect your parts and stability. Most low end psu will have poor qualiry protection circuits or complete lack of them all together. I have seen low tier psu's from name brands with ripple of above 50% of range of spec.