PC powering off at night

[scottws]

I just started having trouble about two weeks ago where my desktop PC is powering off at night. Not every night, but I would say two out of three nights or three out of four.

A few days ago, I went to go on the PC around 7:30am and it was off. I powered it on and it gave me the error that Windows was not shut down properly, but it booted normally. I checked the Event Viewer and there was a non-error/non-critical event logged at around 5:20am the same morning. So it happened between that time, obviously.

I have no idea what is causing the issue.

Here's what I know so far:
+ The PC has never once shut off on me while in use.
+ The Event Viewer does not show a big list of stopping services logs, which would indicate a soft shutdown of some kind. It seems to be a hard power off.
+ I don't run SETI@home or have any CPU- or GPU-intensive tasks set to run at any time during the day. There is a virus scan scheduled for once a week and a defragment once a month, but that's it. The only thing that runs during idle time is indexing.
+ I have played games like Crysis for hours with no power off. The PC's fans spin like crazy from the generated heat, but I've never had a lockup or power failure running a CPU- + GPU-intensive task like a modern game.
+ This PC is plugged into a APC SmartUPS 1000. I have another PC that acts as a server running some virtual machines and that one is only plugged into a surge protector and does not power off. So it is not a power blink causing this problem.
+ The PC is about a year old and there are no software or hardware changes that coincide with this issue.
+ The temperature in the house goes down at night.

OS: Windows Vista Business x64
CPU: Intel Core 2 Quad Q6600
Chipset: Intel P965
Motherboard: Asus P5B-E
Power Supply: Antec TruPower II 550W
Video Card: EVGA GeForce 8800 GTS 320 MB
RAM: 4x 1 GB OCZ DDR2 800

 

[webada]

So, what is it doing powered on during the nite? what is it indexing? and how much of workload is that during indexing?

Did you try to leave it on and let it do absolutely nothing?

Did you try to leave it unplugged to UPS and to surge protector directly?

Other things but I think you have them covered:

I would check power management but since your said eventlog indicates abrupt shutdown.... well, doesn't hurt.

also, make sure power management is not turned on via bios, Os should handle this function.

 

[scottws]

I'll try the surge protector idea for sure.

As for the indexing, is just the normal indexing that Windows XP and Windows Vista do for file searches. I don't attribute this problem to that, because my PC is idle during the day as well and I only discover it shut off in the morning, never after work.

 

[thegisguy]

I second the UPS idea. I had a system a few years ago on an old UPS and it would randomly reboot. It drove me insane, I finally paid a local computer outfit to test each part. When everything tested out fine the tech asks "Do you have this plugged into a surge protector or UPS...". Getting a new UPS solved the problem for me. Hope it does for you too.

 

[scottws]

Well, after I got home yesterday, I moved the PC from the UPS to a surge protector. It did not shut down last night. I don't want to cheer just yet... the next few days will be very telling. But it's certainly something that generates some hope.

 

[webada]

good luck, keep us posted

 

[scottws]

Yeah, I think the UPS was the problem. It hasn't shut off since moving to a surge protector. Yay! Thanks for the suggestion.

Now the question is, what do I do with this UPS?

 

[corkyg]

I have found that not using the USB link and automated functions of a UPS make it much more reliable. I just don't install any of that software, and strictly use the UPS in a "manual" mode.

And, if your UPS is 3 or more years old, it may simply need a new battery. Today, it is often better to just replace the UPS.