Help! Computer spontaneously reboots after reaching desktop

[AppleTalking]

I've been fighting this problem ever since last Friday afternoon, but to no avail. It seems that almost every time my computer boots up, it gets up to the login screen, then loads the desktop, then spontaneously reboots. This has happened under my current installation of Windows XP Pro and a new, clean installation (after reformatting the drive) of Windows 2000. I have the "automatic reboot" option unchecked, so I think that I would be getting a BSOD if it was a software problem. Occasionally the computer won't even POST correctly, simply hanging either at the POST screen or the video card BIOS screen with the hard drive light stuck on. The few times that it does boot up to the desktop successfully, it will reboot within 30 minutes. Nothing about my hardware configuration has changed in at least a month or two, so I know it's not a problem with new hardware.

I have tried to boot it up with as many cables disconnected and cards pulled as I can, but the thing still reboots. There are no messages in the Event Viewer to indicate an error (just: "Microsoft Windows 2000: Uniprocessor free" over and over again) has occurred, and I never get a blue screen. I have updated my motherboard to the latest BIOS, but still the thing insists on rebooting. Nothing in my system is overclocked, and the CPU temperature never gets above 50C. Here are my complete system specs:

Enlight 7237 case with 300W Enlight power supply
Epox 8K7A motherboard (AMD 761/Via 686B chipset)
AMD Athlon Thunderbird 1200MHz. processor (not overclocked)
512MB Crucial PC2100 RAM (passes memory checks at POST)
40GB IBM 60GXP hard drive (amazingly, no real problems with this yet)
10GB 7200RPM Maxtor hard drive
AOpen 12X DVD-ROM drive
Yamaha 8x4x24 CD-RW drive
Generic floppy drive
Hercules 3D Prophet 4500 graphics card (Kyro II chipset)
Turtle Beach Santa Cruz sound card
Texas Instruments FireWire card
Linksys 10/100 NIC

USB Devices: Microsoft IntelliMouse, Symphony HRF adapter, Samsung ML-1210 laser printer
PS/2 Devices: Microsoft Natural Elite Keyboard

I'm willing to bet that it's either the power supply or the motherboard that's at fault here, especially since there's no blue screen. Any help you guys can give would be greatly appreciated. Thanks!

Nick

 

[Markfw]

Try a really slow generic 1-4 meg PCI video card (a couple even). Try that as your only card in your next test. If that doesn't work, then I would guess your memory is bad. You could also swap that out, but most people don't have extra memory laying around. The viedeo card you can get out of an old system, or buy one for 5 bucks at a used PC parts store.

 

[AppleTalking]

Thanks for the suggestion, Markfw900, I hadn't thought of the graphics card yet. I actually had kind of a "duh" moment when you mentioned it, considering that the problems didn't start on my new clean installation until after I had installed the graphics card drivers. The few times I've booted it up into safe mode too, it has seemed to be okay. However, since this is the same graphics card and drivers that I've been using for a year now, I wonder if a flaky power supply or motherboard could be causing the graphics card problems. What does anyone else think?

Nick

 

[AppleTalking]

Bump for more information:

During one of the few times my computer actually stayed up after loading the desktop, I downloaded 3D Mark 2001. As soon as I run the demo, the computer reboots. Doesn't even get to the first scene, just reboots. Also, if I uninstall the graphics card drivers and revert to standard VGA, the box seems to stay up - I tried rebooting the machine 10 times, with 20 minutes between each reboot.

I'm on the verge of buying a new graphics card here, but before I do, I want to make sure that I'm not missing anything. Is there anything else that could be causing these problems? Any other tests that I should run? Please help, thanks.

Nick

 

[Bovinicus]

It sounds pretty evident that the video card is your problem. Try setting your video card to AGP in the BIOS, though I doubt that will do much of anything. Also, make sure you have the latest drivers for the card. It sounds to me like your video card has some component on it that is failing. Sorry to hear that. May I suggest the Radeon 8500/8500LE as your next card? I have one, and I love it.

 

[IanthePez]

I have had many new video drivers cause this to happen to my computer. Perhaps it was just a driver issue? May want to make sure before you pay anything for new hardware.