PC shuts off after starting

[t0m3k51]

I'm working on a friend's PC. It's a custom built machine, about 3 years old.

This is the mobo, XFX nForce 750a SLI

Basically, the PC shuts off after trying to boot from the hard drive or CD or DVD.

I swipped the PSU, hard drive (IDE & SATA), DVD/CD drives (SATA & IDE), still during booting the PC turns off.

The board looks clean, no leaks, the cables are all connected. I removed the video card and connected the LCD to the board's DVI port, nothing.

Memtest86 shows that the ram is OK.

Tried loading Win 7 and XP by doing a clean install, 7 stops and XP continues, but the PC shuts off about halfway thru the installation.

Tried Ubuntu Live CD, once the Ubuntu screen shows up the PC shuts off. At that moment I can feel the mobo under the processor is really hot despite the PC has not been running today at all, only the Ubuntu Live CD is the first thing I ran today.

When I access the BIOS everything seems fine, last night I left the PC in BIOS for 3 hours and it stayed ON. I reset all the BIOS setting to FAIL SAFE, still PC shuts off.

HELP!!!

Is the mobo going bad or the processor?

 

[Slugbait]

This is usually because the proc is overheating. The heatsink possibly needs to be re-seated...might as well clean it and reapply thermal grease as well.

Considering it doesn't power down while in the BIOS, there is also the possibility the fan is going bad and doesn't speed up enough to cool the proc when doing something else.

 

[t0m3k51]

At this point, the CPU temp gets to 48 degrees C in the BIOS, and the PC turns off on its own.

 

[llee]

Take all the parts outside of the case. You might have a grounding problem.

 

[t0m3k51]

I'll wait til morning. I'll pick-up some thermal compound, apply it and reseat the heatsink. Then I'll go from there.

 

[mfenn]

This is usually because the proc is overheating. The heatsink possibly needs to be re-seated...might as well clean it and reapply thermal grease as well.

Considering it doesn't power down while in the BIOS, there is also the possibility the fan is going bad and doesn't speed up enough to cool the proc when doing something else.

:thumbsup:

 

[t0m3k51]

OK, thermal compound applied. Now, the DVD drive doesn't work, and I do not see anything on the screen. It's all BLANK. Tried the DVI and VGA ports. Says no signal coming from PC.

 

[t0m3k51]

Nothing is POSTING.

 

[RipGlitter]

This is usually because the proc is overheating. The heatsink possibly needs to be re-seated...might as well clean it and reapply thermal grease as well.

Considering it doesn't power down while in the BIOS, there is also the possibility the fan is going bad and doesn't speed up enough to cool the proc when doing something else.

That is what I would have guessed right there, heat.

 

[llee]

Take all the parts outside of the case. You might have a grounding problem.

Did you try the above?

 

[t0m3k51]

I scrapped the whole project, replaced the mobo & cpu.

 

[piasabird]

Sometimes intermittent shutting off or a cycle that causes reboot can be caused by driver issues and registry errors. I have seen issues like this from older DVD drives.