Automatic System Powerdown

[bobobear]

Not too long ago, I had thought my motherboard blew up so I bought and installed a new one.

The system boots up fine and the OS (Windows XP) loads up. After a period of time though (5 minutes, 15, it varies), my screen suddenly goes blank, and I can hear my hard drive stop spinning. The fan still runs, though, and I have to either press the power button or turn off the ATX switch to shut off power.

Now I know my hard drive is fine: when I transfered it to another computer, it loads up fine with no problems.

I also know it's not the mother board. In fact, the previous mother board was just fine as my computer was suffering from the same problem. The only difference was that it powered off 10 seconds into the initial power up.

So it's either the processor or the power source, and possibly the fan/heat-sink. I just don't know which. I'm less inclined to believe it's the processor, but I don't want to go out and buy a new power supply and/or heat-sink/fan if the real problem was the CPU.

Or is it a software problem? I highly doubt this. But at this point I have no idea.

[gussery]

Is it powering down after a short period of inactivity or are you busy using the computer when it occurs?

Have you scanned your system for viruses and malware?

[bobobear]

No virus', spyware, etc. It doesn't power down due to inactivity: I've changed the power options to never power down (either main computer or monitor, etc). But it shuts down whether I'm working with an application or not. Mind you, I haven't used the new motherboard-ed computer very often as I'm afraid of damaging some system component everytime the power dies.

I know it's not entering standby mode, since the sound of both are extremely different. In standby/sleep mode I can hear the monitor go, then the disks shut off moments later. When my computer powers-down, I hear a pop (and it's a worrisome pop sound), then everything shuts off simultaneouly save the fan and the power LED. The light remains on, and I have to hold the power button for a few seconds to turn everything off. Of course, once I do, I can't turn the sucker back on until I shut down the entire computer (turning of power box) for a good 30-45 minutes.

[gussery]

Sounds heat related and/or power supply related.
How big is your power supply?  Have you cleaned it with clean canned compressed air lately?  How about the CPU fan?

[bobobear]

No, I've never cleaned it with clean canned compressed...which may be the problem since the system is over 2 years old.

The CPU fan seems to work fine, though. I have no idea what the heat-sink does (presumably conducts heat away from the chip?? just a novice here) and whether it can independantly malfunction from the fan.

350 Watt power supply. Specs here since I don't know what's significant or not.

[gussery]

Does you BIOS contain settings for chip temperature and power down?  If so you may want to monitor the chip temperature and see if that coincides with the shutdown.

BTW, your assumption is correct on the heat sink.  An incorrectly installed sink and/or fan can actually make you chip run too hot.

[bobobear]

Not that I'm aware of. I tried to check, but moments after I loaded the configuration screen, everything just froze. No hard drive was connected this time, but there was an audible change in the fan/heat-sink sound. It sounded like something had shut off, or the fan noise quieted down.

I'm while I'm leaning towards replacing the heat-sink and fan, in the back of my mind I still think it could have something to do with the power supply, or that my processor (3 year old intel celeron D 2.2 Ghz) is creating problems.

[Kablam]

What spec is the rest of your p.c If it is pretty high then it could be the power supply. i got the same problem when i installed my new graphics card that needed a fan. my psu was on 300W though. Try unplugging your c.d drives to test it and see if the problem remains

[bobobear]

At the moment, no drives except the floppy are plugged in. It's a really basic system, put-together (Soundblaster Live, firewire card, 512 RAM, Asus p4 w/ usb+lan+vga out, 2 maxtor hds, and a dvd writer) and I've never had problem with this setup until recently. Which I thought was caused by the motherboard "blowing up" (the previous one was an ECS model).

The new Asus mobo has an internal power LED which remains on after everything suddenly powers down. I don't know if it means that the power box is not the issued.