PC Shutting itself off

[Kodiak]

I leave my PC on 24/7/365. I wake up two days ago to have my PC off. I ignore it, and the next morning, I wake up, and yet again it has shut itself off. I'm beginning to be concerned. I get HP today, and read for a few hours, come back, and yet again, my PC is shut off. Nobody has been home or awake when it shuts off, but me. I checked my Power settings, and it is still set to Always On.
I'm running WinXP 64-bit
AMD 3000+ S939
1GB Kingston ValueRAM
Gigabyte 6600

I'm beginning to think its my power supply, which came w/ my $30 case I got off Newegg.

My Case

If you guys have any suggestions on how to fix this or what to do, I'd greatly appreciate it.

Thanks.

 

[SGtheArtist]

We'll need more information.

What is the computer running when this happens?
Have you changed anything around the time it started?
Is the PC on an UPS?

 

[Kodiak]

1) Typically mIRC and Trillian
2) No
3) No

 

[Kodiak]

 

[The Linuxator]

Based on the lack of given info I will give you a long general list of suggetions and try whatever applies:

1- A certain component on your motherboard/ or attached to your motherboard is overheating if its not your CPU then it can be your northbridge chipset which in some motherboards these days which dont have Active northbridge cooling do overheat their chipset and as a protection mechanism you bios will intervean and shutdown the pc once max tempareture is reached.
2-even though you said you have never changed any settings which also indicateds that you didnt not change you BIOS power settings, but sometimed you see some bios resetting to default settings due to an error or some kind of failure check your BIOS settings and make sure nothing indicated what I am assuming.
3-check wiring connections for fans also check voltage settings for cpu and northbridge, also be sure nothing apparent is casusing a short circuit on the long run , like loose exposed wires if u need to u can check motherboard mounting points to the case sometimes it can be the cause.
4-check try using a different PSU maybe your doubt is right and its defective, dont forget to check external power connectors for any loose wiring or plugs.
5- If hardwrae and connections seem to be ok then see if windows could be the problem the best way to check without reinstalling windows again is to get your hands on a live linux cd I hope you are familiar with linux. put it in your computer boot from it and let it load and login to it and go to sleep and keep it running(make sure you have the power settings in linux set to always on) if you wake up to find that your pc is still running then we have isolated the problem to windows all you have to do is reinstall it.( A link to a popular Live Cd )

note: If you are unfamiliar with linux, or cant get your hands on a live linux cd then you can try a simple but not a good simulation of your pc running an OS you can boot into BIOS and go to sleep from there and If you wake up and the pc till running then we know your hardware isnt the problem.

Final note: If all the above approaches yielded negative results then maybe you should try not sleeping perhaps you are sleep walking in your room and going to the pc and shutting it down yoursel,a video camera mounted next to you pc can assist with the recognition of the problem f.

or

maybe the pc gets gealeous from you sleeping all the time and decides to do the same.

 

[amdskip]

+12v line is rated at 15 amps, that is very very weak. Even if the problem is not your power supply (which I believe it is) you should replace it with a much higher quality power supply (do search in general hardware for power supply opinions).

 

[Kodiak]

Kodiak is teh broke

 

[SGtheArtist]

Another thing to consider since you're not on an UPS is that your power at the outlet is fluxuating (sp ) such as a brown out were the power dims but doesnt fully go out as with a power outage. Brown outs can cause the PC to shut down.

I personally think your power supply should be plenty for the hardware you're running on it. Does Windows do Automatic updates? I've heard that the 64bit version needs special drivers It could be driver related.

How many years have you run the PC continuously? If its been less than a year then I'd say its drivers or Windows updates. If more than a year it could be your PSU. Definately consider the brown outs I mentioned though, it might just be as simple as implementing an UPS.