PC shuts down in Windows 7 full mode

Does anyone know what causes my PC to shutdown in Windows 7 full mode after only a few minutes of booting up yet will run in Safe mode indefinitely. I have reset the BIOS to default, run various antivirus procedures, run Malwarebytes etc. but to no avail. The PC is an HP s3240uk which admittedly is old by today's standards but had been very reliable until the last few days when this problem reared its ugly head. Any practical suggestions?

Does it shut down gracefully or not?

Overheating cpu caused by heatsink clogged with debris?

In reply to a post by petsy:

Overheating cpu caused by heatsink clogged with debris?

Indeed, if its the latter answer to my question that would be my first guess.

I had already assumed that the CPU was possibly a factor and cleaned out any dust etc. but to no avail. The PC shuts down without warning yet runs well in Safe Mode.

In reply to a post by petsy:

Overheating cpu caused by heatsink clogged with debris?

Have considered removing CPU and refreshing the thermal paste but didn't want to do this without first checking other options.

More likely to be an errant device driver. Are there any clues in the event log?

In reply to a post by BatBoy:

More likely to be an errant device driver. Are there any clues in the event log?

Will check, but as a point of interest I note the warning 'device driver software was not successfully installed' appears when starting in full mode. This seems to refer to the mass storage device which relates to the built in card reader. I have no idea as to how this could have occurred because it is part of the HP setup which until these recent problems was never an issue!

In reply to a post by Pipexer:

Does it shut down gracefully or not?

It does not shut down completely without me holding the power down button. Another new discovery ... I was running an instructional video in full mode via YouTube when suddenly the PC shut down without warning. However, the odd thing is that the sound continued after the shutdown. What does this indicate ... maybe the passively cooled graphics card is overheating? It runs at around 65 degrees C but I can't recall this being much lower.

If the sound was still going then the PC hadn't shut down. It suggests you have a monitor or graphics card problem as it seems it is the screen going off rather than the PC.

In reply to a post by ian72:

If the sound was still going then the PC hadn't shut down. It suggests you have a monitor or graphics card problem as it seems it is the screen going off rather than the PC.

Thanks Ian. Am I correct in understanding that the monitor and graphics card could still run OK in Safe Mode regardless of such problems?

Don't think the specific driver loads in "Safe Mode", just standard MS vga driver.

Have you tried updating your graphics card driver?

Could also be that a lot of graphics extensions won't run in safe mode and therefore whatever is tripping it out is not actually operating.

Agree about the drivers - would be the first step. My mentioning monitor is unlikely after the reminded that it is ok in safe mode (had forgotten that part of the thread).

In reply to a post by broadband66:

Don't think the specific driver loads in "Safe Mode", just standard MS vga driver.

Have you tried updating your graphics card driver?

Did this three weeks ago but have just thought of something else. If the monitor is the cause why would it work in Safe Mode?

In reply to a post by WatchMan:

In reply to a post by broadband66:

Don't think the specific driver loads in "Safe Mode", just standard MS vga driver.

Have you tried updating your graphics card driver?

Did this three weeks ago but have just thought of something else. If the monitor is the cause why would it work in Safe Mode?

Oops, just read Ian's comment re: Monitor in Safe mode. Thanks for suggestions though. I am now seriously considering a new graphics card but not sure if any would be compatible with my HP s3240uk desktop. It would have to be low profile and have a small bracket to suit.

If you are confident it is worth trying the graphics card then I could recommend talking to Novatech. They have some very knowledgeable guys and should be able to point you to a card that would fit your machine. Be aware though that this is a likely cause rather than a definite cause so it may be that a new card doesn't fix the issue.

Have you got a CEX (2nd user) near you. They usually have various types of graphics cards.

In reply to a post by ian72:

If you are confident it is worth trying the graphics card then I could recommend talking to Novatech. They have some very knowledgeable guys and should be able to point you to a card that would fit your machine. Be aware though that this is a likely cause rather than a definite cause so it may be that a new card doesn't fix the issue.

I have borrowed a low profile card from another more recent PC which seems to have done the trick so am almost certain this is the answer. Will update you with results of my tests with a new card.

Excellent, good you could borrow one to prove it before paying out cash.

Post deleted by Sadoldman

Post deleted by Sadoldman

In reply to a post by ian72:

If you are confident it is worth trying the graphics card then I could recommend talking to Novatech. They have some very knowledgeable guys and should be able to point you to a card that would fit your machine. Be aware though that this is a likely cause rather than a definite cause so it may be that a new card doesn't fix the issue.

SOLVED!! In instances where the sound continued after the screen went blank made me confident it was not a PC shutdown. After a successful test with a borrowed card from another PC I decided to take the plunge and bought a new graphics card. Tests since fitting this card have proved positive with no more issues of a blank screen.

Thanks for all your suggestions.