Motherboard or CPU?

[crowndale]

I've had a home-built PC running since January with an ASUS P4P800 motherboard & a 3Ghz Pentium 4 processor, and until recently it was fine. About a week ago Windows XP closed itself down for no apparent reason a couple of times, then a few days later it got to the point that the machine would shut down & reboot every few seconds, not even getting any display to the monitor.
Took it apart and found that all fans came on when the power applied to the system (start button not pressed) but just for a few seconds then, after a few more seconds, the process would repeat about 3 times. Pressing the start (power on) button would trigger the same process with the same result.
Took motherboard out of case and tried with everything apart from RAM & processor removed - same result. Bought new power supply - same result.
There are no beeps, even with RAM removed it's exactly the same.
Tried with video card installed, and about once every five attempts I briefly see the ASUS splash screen before the system shuts down again.
Help - please!!!! It can only be, I think, cpu or motherboard but which?

 

[paparazi]

crowndale
I can only think of a few of things
1) That the motherboard is having problems picking up the RPM signal from the CPU fan (try another fan) and check connection to the CPU fan header.
2) Bad ram
3) Addon card, cdrom or other plugged in device (USB/IDE etc) is causing reboot (once had a firewire CNR/ANR card do this on an Asus board)
3) Overheating (heatsink not fitted correctly and with paste)
Martin

We like members to GIVE and not just TAKE.
Participate and help others.

 

[lesgray]

I'd think the motherboard is the problem. THe P4's will automatically clock themselves down if they overheat, so as to not burn up. That should give the motherboard plenty of time to boot up at least.

Les Gray

http://www.creartec.com

 

[crowndale]

Thanks guys

It can't be ram as I've tried various combinations, including no ram at all, and I've also taken out all addon cards. However your first & last points, Martin, are both worth following up. I've just got back from PC World to get some thermal paste, but they've sold out!

Nice point about the P4, Les. If I've no success with Martin's suggestions then I'll sent the motherboard back as a warranty claim and see what Aria make of it.

Thanks again
Peter

 

[gbaughma]

If you're not getting all kinds of beeps when you attempt to start the system with no RAM, it's the MOBO.



Just my $0.02

"In order to start solving a problem, one must first identify its owner." --Me
--Greg