XP pro random restarts!

[wverb0783]

So i've been working on a clients computer. they are having random restarts. it doesn't seem to have any particular time or event when it occurs. i have checked event viewer, as well as ran extensive, memory and CPU tests. i have swapped out the PSU for a known good one to no avail. the computer will not shut down if you are running a test off a bootable cd or if in bios, but will shut down if in windows? could this be the hard drive itself? any help would be appreciated. this is running windows XP Pro. pentium 4 system, 256 mb ram, pretty basic system.  Thanks.

[patio]

First travel to Control Panel/System/Advanced/Startup and Recovery...uncheck auto restart on errors which is on by default.
Now instead of random restarts you should now get the wonderful BSOD error screens...
Write down the entire message and post it here...it will help narrow things down in the diagnosis.

p.s. Another very common cause of restarts are heat issues. Remove a cover and see how dirty it is inside...check to see all fans are operating properly.
If it is dirty use a can of compressed air to clean all heatsinks and fans. Use a QTip to hold the fan blades in place while you are blasting them.

[wverb0783]

Its not too hot, i've eliminated that. all fans heat sink and processor are clear and cool. i also reseated the cpu, with new paste to insure this. i cannot get far enough into windows at this point to turn that feature off.  or i would have. thanks for the reminder though. also do you think this could be caused by the hard drive?
 

[Fed]

it doesn't seem to have any particular time or event when it occurs. i have checked event viewer,

i cannot get far enough into windows at this point to turn that feature off

Is it getting worse or am I confused?

Will it run in safe mode?

[wverb0783]

At this point, it seems to be shutting down a few seconds after you see the windows xp loading screen.  in an attempt to reinstall windows. it will shut down after setting languages, and such during installation. when it does shut down, the PSU fan stays running and front power LED remains on. but all other fans shut down, and it loses power to all cd rom drives as well as hard drive. thanks for your help, i am beginning to think it is the motherboard, not sure what else it could be. i have tested absolutely everything, and tried 3 different hard drives, as well as 3 different psu, tried different CPU. and ram. i'm at a loss.

[Fed]

I think your problem is heat related and it probably lies in your heatsink fitment or thermal paste application.
Don't be offended but are you 100% confident that you have installed the heatsink and thermal paste correctly?

[wverb0783]

yes i'm sure. not only that. the processor on this system isn't one that runs hot to begin with. and like i mentioned i've tried multiple CPU's and heatsinks. same result. i'm leaning toward the motherboard at this point

[Fed]

So long as you're sure, something to think about...
If a heatsink feels cool then it probably doesn't have a good thermal connection to the CPU.

[wverb0783]

alright, as i said it's not the CPU overheating. it's running at a maximum of 36 C under load. it seems odd that the thing will stay on for hours, if i'm not trying to do anything with windows, or with xp disks. but as soon as i do an installation, part way through. ( after the setup files are done transfering and computer resatrts) it shuts down.

[wverb0783]

YAY!!! i found the problem! i so overlooked this and wont do that again. so upon closer inspection of the motherboard i noticed that about8 capacitors are bulged on top and beginning to leak. i know what you're thinking how didn't you notice, but the fact is it never really crossed my mind. i looked over it and because they are just starting to bulge i missed it. Thanks to all who helped.   

[linuxlover]

I think that's easy enough to miss. Those capacitors sure are small. (and even if they aren't theres quite a few of them to say the least.)

[Fed]

What motherboard is it?