CPU Fan Stopping/CMOS Acting up/Motherboard failure?

[eneogei]

So as of two days ago, after moving to a new place, I plugged my computer in and it ran fine for awhile, but after about thirty minutes it blacked out, which was quite puzzling indeed. After turning it back on and removing the side of the case to see what was up, it seemed that the CPU fan would shut itself off and then the computer would shut itself down soon after to save the CPU.

I have SpeedFan on my computer, and so I let that program run for awhile, seeing that the fan would every so often shut down, so I'd bring that fan's control bar back to 100% and the fan would resume running at 100%. The fan would shut off every few minutes, but could be brought back to life by commanding it to through this program. Shortly thereafter, I rebooted and CMOS reset itself, and on another reboot the computer announced that all of my hardware was new and had to re-recognize it all.

A CS major and I have been trying to figure this out for the last couple of days, and have come to believe that either my motherboard has a defect, the CMOS battery is dying, the power supply is giving out weird voltages, or the CPU fan is dying.

Any thoughts?

Here are its specifications (I built it new about one year ago):
2.8gHz Intel Pentium 4 Socket 776 (I think!) CPU
Soltek motherboard
80gB HDD
512mB DDR RAM

 

[firewolfrl]

replace the fan. cpu may be on the way out soon (or is already gone) if you don't.
it only takes a few seconds for the cpu to die of heat.

 

[garebo]

Of course its easy enough to check and make sure the battery is near 3 volts as it should be.
I can also suggest you take everything out and clean it all and put it all back in. Clean fans and cpu fan and heatsink of all dirt and put new thermal goop on the cpu.
Start with a bare setup and add one item at a time, wait a day or 2 between each one if there are no problems.
You would need a digital or analog multimeter to check your power supply rails. A good tutorial for that is at techrepublic.com. Its a great place, you do have to sign up but they wont bug you, its professional like this place.
Check your bios and make sure that if there is a bios temp setting at which your cpu will shut down, make sure that temp isnt too low.


Good advice + great people = tek-tips

 

[paparazi]

eneogei
A few things spring to mind:
Remove this software (speedfan) if you can control the fan then it is possible that the software can be causing the fault and shutting off the fan.

Go into the bios and check for any sort of SMART FAN controls, these are designed to cut down on noise levels when the PC is not under load, disable any of these options.

Obviosly check the mechanics of the fan, is it blocked up, or does it have any resistance to turn, it's not unheard of for a fan to go faulty so I would replace it straight away to be sure.

It is unlikely that the PSU is the cause because most fans "starting" voltage are around 6Volts so for the fan to stop this would have to be lower than that, all sorts of other periferals would be effected.

Most likely caurse after everything else is checked, is the motherboard unfortunately.

I'm wondering if you could bypass the CPU fan header and wire the fan directly to a PSU molex connector (you may need to leave the yellow fan rpm sensor wire) attached to the CPU fan header so the motherboard still sensors a spinning fan.

Martin

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