Power Supply Fried?

[Dukes]

Alright, so I left my computer on while I was at work about a month ago and when I came back it was truned off and wouldnt turn on again. I thought it was a power surge and tested it out with a power supply from another computer. I disconnected all the drives and just pluged the supply into the motherboard. Everything turned on fine including the fans so I bought a new supply. When I hooked everything up, the computer wouldnt start again. It only starts up when I plug into the 20 pin adapter on the mother board. If I hook the supply to anything else, the fans and CD-ROM turn on for a seccond then die. Any suggestions? Is my motherboard fried?

[Ken_ver_1_5]

test the devices one by one if it powers up with just the motherboard
try the mb and floppy. if its a no go try mb with the hard-drive. keep
testing till you find the device that is causing the problems and replace just
that part.