Bad Power Supply, or Motherboard?

[lutherl]

I have a Dell Dimension 9150 that will randomly cut off while running. The power button blinks orange, nothing is running, there are no diagnostic lights, and it usually won't boot until a day later. I've narrowed my problems down to the power supply and motherboard. Oddly enough, the capacitors look fine on both. No bulging or leaking. I've already cleaned off the whole computer and dusted it. Dell said orange power light could mean power supply, or motherboard failure. Which do you think it is?

 

[basroil]

If it's in warranty period, have them replace both. If it's not, you should try removing as much load from the machine as possible (graphics, extra disks, etc) and seeing if the PSU load changes things (if it does, more likely it's PSU, if it doesn't, more likely it's mobo). Of course, if you have a spare PSU that's the easiest way to know.