Problem with cpu fan

[srkia]

I have Asus motherboard with AMD Athlon 900MHz. When I switch the computer on for the first time the cpu fan won't start spinning. But when I turn it off and then on again, it starts. On every other turning on/off the fan is spinning. The problem only occures when I leave the computer switched off for at least an hour. I replaced the fan with the new one, even tried to plug it in the auxilary fan socket, but it stays the same.
Do you have any ideas what could be causing this?

Thanks in advance!

Srdjan

 

[MrCoffee]

Might be the PSU, I heard of this sort of thing before, can't remember solutions, you might want to search through the forum.

 

[RJteCH]

Did you build this one yourself? How many watts is your power supply? Sounds like your components are being forced to randomly share power or something. I don't really know, this is a first for me.

 

[srkia]

Yes, I've built it myself, but it has been working without any problems for the past three years. The problem first occured a few days ago.

 

[dipique]

What PSU do you have? Are there a lot of components drawing power?

Dan