PC powers off

[alegator]

I have a 2nd PC that runs fine (not the one in my computer details), except that whenever I run a task that demands above normal or high CPU usage (like malware scans, defragger, etc), it shuts down forcing me to power it on again.
How can I fix this? Maybe changing some BIOS settings?? I suspect it might be the CPU fan not working efficiently as it should or some other thermal issue hardware related, in which case a simple BIOS setting change won't do it.
Any ideas? Thanks

[IKnowNothing]

This sounds suspiciously like the CPU overheating

Try cleaning the cpu fan - ie blow and dust out of it - and see if that helps
Otherwise you could try changing the fan and adding new grease.

[redwudz]

Try a temperature reading program like HWMonitor: http://www.cpuid.com/hwmonitor.php Load temps: 60C- 50C is OK but high, lower is better. 25C - 35C would be very good. Much over 70C and you may have thermal shutdown by the MB or the CPU, or at least throttling, which will slow the computer. You can also check temperatures in BIOS with most motherboards, but not under a load.

Feel how much heat is coming out the the power supply and exhaust fan. That should be warm, not hot like a hair blow dryer.

Pull the side cover off and blow a desk fan it there. If it takes a lot longer before shutting down, it's likely thermal.
Check for dust and operating fans while you have the cover off also. And clogged air intakes. And check how much heat is coming out of the CPU fan. If you can't hold your finger at the base of the CPU cooler for about a second, it's probably too warm.

If it is a thermal problem with the CPU, your thermal compound can wear out quickly with a lot of overheats. You might have to change that or just put in a new CPU cooler if what you have is inadequate.

If you're not overclocking, about the only settings in the BIOS that will do you any good are the fan settings. You can usually set them to run full speed all the time if you need better cooling. But that doesn't sound like the problem.

[jimmalenko]

I used to see similar behaviour (lock ups, unscheduled shut downs etc etc) and it was generally CPU overheating, and generally Celeron processors seemed to go a lot quicker than the P4s that were a similar age.

[alegator]

Thanks everyone for their feedback.
Redwudz, the PC forcefully shuts down (screen goes black) with no BSOD.
I just finished cleaning the internal parts of the PC, there was dirt beyond imagination, to the point of clogging all fans (CPU and case fans). After cleaning everything, I ran CPU intensive tasks and no shut down. I hope things keep stable. I will download your suggested monitor and post temperature results.
By the way, this is the MOBO of the PC:
http://www.msicomputer.com/product/p_spec.asp?model=PM8M2-V&class=mb
On a separate note, I installed hwmonitor in my main PC (see computer details) and it only reports temperature for the hard drive. Does it mean that my CPU has no sensor?
Thanks.

[alegator]

Good news! The PC has been running smoothly for 24 hours with no shutdowns. Furthermore, I installed HWMonitor and CPU Burn-in and ran the CPU at 100% usage for 30 minutes and everything stable. Before the Burn-in the CPU temp showed 45 degrees celsius and it reached a maximum of 64 degrees during the burn-in test. The fans also responded well by increasing the RPM during the burn test. So apparently the cleaning of the fans+case solved it.

[redwudz]

Most CPUs have had temperature sensors for quite some time, AFAIK. Earlier CPUs had them under the CPU socket, but a P4 should have it on on the CPU die itself. Either HWMonitor didn't detect it or it's not working. Not a major problem unless it's prone to overheating. You could also check the BIOS as most have a hardware page that lists temperatures.

It's worthwhile to check for dust in a PC several times a year. If you wait too long, it's hard on the PC and the dust may get really stuck down and a lot harder to remove.

[alegator]

Most CPUs have had temperature sensors for quite some time, AFAIK. Earlier CPUs had them under the CPU socket, but a P4 should have it on on the CPU die itself. Either HWMonitor didn't detect it or it's not working. Not a major problem unless it's prone to overheating. You could also check the BIOS as most have a hardware page that lists temperatures.

I checked the BIOS and there's no section on CPU temperature. I also tried some other hardware scanners (PC Wizard2008, Lavalys Everest,SiSandra, DrHardware,SpeedFan) and none report CPU Temperature, only HD temperature. I suspect that my system does not have a CPU temperature sensor.
UPDATE: I just found out through the Dell Forum that my system came without any CPU temp sensor