A long while back i think around November 2009 my computer started rebooting after 5 seconds of being fully shutdown. The only way to stay fully shut down is to flick the power supply switch in the 5 seconds when it is off.
Mother board: ASUS P5Q
Video card: ASUS EN9800GT MATRIX (nvidia 9800 chip-set)
CPU: Intel(R) Core(TM)2 Quad CPU Q8300 @ 2.50GHz
Network card: Broadcom 802.11g Network Adapter
OS: win7 ultimate 64
Let me know if u need more info about any specs.
I have updated my bios for motherboard to the latest version. i turned off restart on error and i get no errors when shutting down (double checked after rebooting in windows). Looking online most cases point to the motherboard being an issue or a network card. i went through and checked to make sure the lan network couldn't wake up my pc and i have gone into the bios to check and see if anything was able to wake up my pc and as far as i can tell nothing is abnormal there.
Check your BIOS for a power setting called something like: Power-on after power-off, and change it to disabled or No. When enabled, this feature re-starts the computer when electrical power is restored after a power failure (or battery back-up) shuts down the system.
There are often several other "wake on" options hiding out in the BIOS under various names ... I think "wake on PME" (Power Management Event) was the one that was doing this to one of my machines a while ago. I apologize if you've already checked them all and disabled them, but that really is the most common cause.
Other less common causes could be the CMOS battery dying (which would return the BIOS to defaults, and if the defaults included a "wake" option set to on, this would happen) .. or the power button itself being stuck or shorting.
i will go and double check the BIOS again right now. A lot of sites mentioned a Wake on Lan setting that i could never find in the BIOS. Is there an easy way to check the power button for shorting? The part i can't quite wrap my head around is how if i shut down fully then flick off the power supply from the back then immediately flick it back on it doesn't restart. if the the motherboard or windows was setting a wake on event would it not start up my computer as soon as i turn the power supply back on?
Hi. I was encountering a problem with my desktop PC, where it kept restarting whenever I tried to shutdown. After suspecting everything from motherboard, BIOS, PSU to installed software, and after trying out several OS and BIOS settings in vain, I found a solution at the following URL that got pretty close to resolving the problem: http://support.microsoft.com/kb/320299
Here's the most relevant extract from the URL above: "If your computer constantly restarts while you are using it, or if you are trying to shut down the computer after it has stopped unexpectedly, click to clear the Automatically restart check box. If you clear this check box, you receive an error message when the computer stops responding. This error message may describe the cause of the problem. You can also review the system log in Event Viewer to view the critical stop error that occurs when the computer restarts."
This method does not completely resolve the problem, but gets you closer to figuring out where exatcly the problem is (which is the stage that I'm at now). And most importantly, it will stop restarting the PC incessantly! Hope this helps.
Apologies for reviving this old thread, but I recently experienced this problem.
Hope this helps somebody in the future.
1. I updated BIOS to latest version
2. Unplugged power cable
3. Reset CMOS by removing battery, touching those 2 pins with a piece of metal
4. Hit the power on button on the computer with the cable still unplugged
5. Put CMOS battery back in, plugged power cable in and power on.