Originally Posted by Vandiyan
The 12V rail was not good enough to handle the Athlon 64's.
Where did you get that piece of information from?
and you haven't even fired it up yet. pretty amazing that a 420watt psu will not handle the 64
you can mount a psu in any possition that will fit. The issue being what possititon is the fans in. There must be enough clearance between the case and psu to allow the currect amount of air flow to be sucked into the psu for proper cooling. If the fan face is too close to the side it will cause overheating issues. The minimum distance for the properamount of air flow with a 60mm fan is about 3/8" from the panel with clear flow all around....an 80mm fan requires 9/16" clearance between the panel and fan with clear flow all around.
if the psu is mounted within those tolerances it would probably be ok but remember that you have restricted air flow from two directions so if it is too close it will probably overheat