Motherboard Install Problem

[mhubbard]

I am installing a mobo to replace a dead one. After installing it would not boot at all, in fact, no power as no fans were spinning. I plugged a new ps into the mobo, same result. I checked my cables for the power and reset switch. Then, tried again, pc went into BIOS. Plugged the original ps back in and BIOS came up. I thought all was well. I went ahead and plugged in the rest of the front panel connectors, speaker, hdd led, etc. and pc came up fine. I powered it off, installed the rest of the devices, and now no power again. I unhooked everything but the mobo and still no power. I disconnected and connected the new one again, pc came up. I connected the old one back, pc came up fine. Went to the bathroom, and pc would not power again..... and I made no changes....weird. Bad mobo or a short somewhere??? How do I check this????

Thanks!!

After further review, I had purchased 2 of these mobo's so I decided to try the other one for fun. Same darn thing. Intermittent.... So now I just think maybe it is a PS issue. One of the PS is a 350 and the other is a 250. Maybe neither are compatible with the ne sempron's?????