Automatic shutdowns and reboots. Can't stay on for more than 15 minute

If the PC runs fine in Safe Mode then the issue is likely a driver. Check System Recovery Options if you have a System Restore point from before the problem began as Windows Update may have delivered a problem update or driver.

If not while I Safe Mode try as many of the Troubleshooting Steps for Windows 7 as possible as these may reveal the problem. I'd first establish a Clean Boot, uninstall and change to one of the recommended lightweight AV's which never give problems, disable that strange Sound card driver to see what happens. Then scour the logs and other system resources suggested.

But I think I would not waste much time before I deleted all partitions during a booted install to Clean Reinstall Windows 7 sticking with those steps which have been used by over a million consumers to achieve a perfect install without a single complaint, or anyone returning with any issues who stick with the tools and methods given.

whs said:

That would suggest that there is no hardware problem. Go to msconfig and disable the startups, then reboot. If that works well, then there is a startup culprit.

If not, same procedure with the services.

If you found that there is something wrong with either the startups or the services, then you have to run them in small groups to narrow the culprit down.

Just tried this to no avail. The only logical explanation I can see left now is my GPU itself or my graphics drivers. Is there any way to narrow it down to this for certain?

whs said:

You could run a GPU stress test.

FurMark: VGA Stress Test, Graphics Card and GPU Stability Test, Burn-in Test, OpenGL Benchmark and GPU Temperature | oZone3D.Net

Impossible. My PC doesn't stay on for long enough in normal mode.

Aren't graphics drivers bypassed in safe mode?

Pauly said:

Yes they are, windows drops back to basic inbuilt vga driver
You could uninstall gfx driver and run basic gfx in normal operation to see how it goes

I'll give that a try tomorrow.