Sudden Restart

[greshoff]

My computer has started to suddenly switch off and then restart - No blue screens - automatic restart is switched off. Any ideas on what might be causing this issue. It has happened when browsing the web, ie computer was not under any stress. All temps look OK. My computer is as follows:

Operating System
MS Windows 7 Ultimate 64-bit SP1
CPU
Intel Core 2 Quad Q9550S @ 2.83GHz 33 °C
Yorkfield 45nm Technology
RAM
8.00 GB Dual-Channel DDR2 @ 400MHz (5-5-5-18)
Motherboard
Gigabyte Technology Co., Ltd. P35-DS3R (Socket 775) 34 °C
Graphics
SyncMaster (1600x1200@60Hz)
512MB GeForce 8600 GT (ASUStek Computer Inc) 51 °C
Hard Drives
932GB Western Digital WDC WD10EARS-22Y5B1 ATA Device (SATA) 32 °C
1397GB Western Digital WDC WD15EARS-00MVWB0 ATA Device (SATA) 30 °C
Optical Drives
Optiarc DVD RW AD-7261S ATA Device
PLEXTOR DVDR PX-L890SA ATA Device

[3DWizard]

Any recent changes to the system ie. hardware or software installations? Is it ONLY when browsing the web? What browser are you using and does it happen in other browsers?

[dangel]

check memory (memtest), check for grounding issues in the case (i.e. check wires, tip case listen for rattles/watch for resets, check rear of motherboard and all connectors), check PSU (not listed above).

Does it actually switch off? As you say it restarts i'm guessing it's actually resetting?

[big_hairy_rob]

It may also be worth checking your graphics drivers. Recently most restarts have been due to graphic driver crashes, but these are usually preceded by a brief hang.

In all fairness do everything 3d and dangel suggest, including cleaning any dust out of your system, as this can also cause shorts.

[emalemon]

I'd start off with booting up, then mashing F8 - disable automatic restart on system failure, then boot as normal. There might be a very quick display of a blue screen that you may be missing, You could post the 0x000.... error code if it does blue screen. Another thing could be a failing CPU but is less likely.

[Larkspeed]

He stated in his original post that automatic restart is turned off.

You don't list what PSU you have.

In my experience most spontaneous restarts (restart with no blue screen or other error) is usually caused by a failing PSU.

As they get older and start to wear out they have a harder time maintaining constant voltage and if there is a dip below a certain level the PC will restart.

This is more prevalent if the PSU does not or barely meets the requirements for the PC it's installed in.

[3DWizard]

Have any luck with this greshoff? Find the culprit?

[greshoff]

Have any luck with this greshoff? Find the culprit?

Thanks for the replies. PSU not the issue. Had further major issues so decided it was a good enough reason to build a new system. I will continue to troubleshoot the old system when I have time

[Demonwar]

Checked the leads for damage, the number of times I had a fault and realised I kicked the plug out of the socket a bit.