system will post sometimes, sometimes not

[kolt]

I have an old AMD 1800+ with a DFI motherboard. When I power the system on sometimes it will post and sometimes it won't. The fans, lights, CD ROM, ect all have power when I throw the switch. I changed the power supply, but the same problem. I have to turn it on and if I don't hear the motherboard " beep " then I turn it off and turn it on again. Sometimes it takes 5 or 6 times off and on to get it to boot up. Does this sound like a motherboard problem?

 

[Jiggz]

It could be PSU or Mobo. So to find out which one, then you need to "bare: the system. Meaning disconnect extra drives, and add in cards. Start with a basic system and see if the system will boot first time. If the problem is the same then it's a mobo problem. Try looking for an updated bios. It could fix the problem.

 

[LED]

Also could be the Case switch or the Mobo grounding out...which means switch replacement or reinstalling the Mobo after you've tried what Jiggz suggested.