BleepingComputer.com: Computer Strangely Shutting "Down"

I have a PC running XP SP3 that has been fine for years. Yesterday, I got the XP Security 2012 "Virus" on the PC. I never started the actual removal portion of it as I knew what it was. So I was going to reboot the machine to safe mode to try and fix. Once into safe mode, about 2 -3 minutes later, the machine shut down. It didnt power off as the power light on the machine is still on and you can hear the fans running but the actual OS dropped and there is no HDD activity and there was an audible shutting down sound when it happens.

Thinking this was due to that same virus, I booted the PC directly to a Linux pre-OS virus scan tool I use to then remove the viruses. I allowed the software to load from CD and walked away. When I came back in 5 minutes later, the same shutdown issue happened again. So I knew it wasnt the OS.

I then booted the PC up and just into the BIOS screen to see what would happen. About 2 - 3 minutes later, it dropped again...

I also need to mention ( not sure if this is part of it or not) that I believe my CMOS battery is bad as every time I completely unplug the system, I have to reset the Date / Time / Sequence of Drive booting and then its fine.

I have also tried the following:

1. Unplugged the computer and booted

2. Unplugged the computer, shut off hte power supply, turn it back on, plug back in and then reboot.

3. Clean out the inside with canned air of any dust or other blockages

4. Removed All External USB devices (I have 3 External HDD attached)


Nothing seems to fix it. Is my MB shot? Should I Just get a new computer? If so, can anyone recommend a decent desktop that I only need to:

1. Install my WinTV capture card in (PCI-E)

2. Be able to capture and author video to DVD

3. Download a lot of information

Those are really the only three things I used it for...

Thanks again!

OK,

No luck with testing tonight...

Changed out the CMOS battery

Blew out all areas of the machine (noticed the heat sync had a lot of dust on top of it in between it and the fan, its clean now)

Boot up Machine, set all values

Machine stayed up (just in BIOS) for about 30 min and then shut down.

Booted up again and saw these temps before it went down again
CPU Temp - 42 - 44 degrees
M / B Temp - 37 - 38 degrees

What I did notice strange is that the CPU Fan and Chassis Fan are running and give RPM speeds, but the PWR_Fan stays at 0 RPM

I checked the Power Supply and the fans are running on it..

Is my M/B shot? -ASUS M3N72-D

Proc / Fan / Sync Issues? - AMD Phenom II X4 940 Black Edition

4 GB RAM

PC Has been running like this for 3 years

Thanks again for all the help!

This post has been edited by Smack2k: 27 December 2011 - 09:09 PM

Try reapplying thermal paste for the processor and make sure heat sink is well seated together with CPU. Swap another power supply and alternately use one stick of RAM module to troubleshoot. Check the processor gold bristle pins for any dust build up also.

Thanks, will give those all shots...

OK,

Apparently that original issue is fixed and now my issue is that after about 25 min, my video drops, but the rest of the PC is fine.

I am RDP'd in right now finishing the virus scan.

I do have a new MB coming, should I get a new Video Card? Also, is there a way to test this card?

Its a EVGA 256-P2-N761-TR GeForce 8600 GTS 256MB 128-bit GDDR3 PCI Express x16 HDCP Ready SLI Support Video Card