CPU: Athlon XP 2200+
MB: ASRock K7VM3
PSU: ATX 375W
Memory: 2x 512MB DDR 266
OS: Windows XP MCE SP2
After working flawlessly for a very long time, I started experiencing computer shutdowns everytime I plugged in USB devices that used the USB port as the power source (iPod Touch and external HDD). I thought this was caused by a defective PSU, which I tried to change for a ATX 500W. The computer failed to start so I then thought the motherboard was causing the problem. Further tests with my original PSU allowed me to pin-point that either the motherboards IDE ports or both my HDD (tried individually) are defective as the computer freezes on the post when either of the HDD are plugged in any of the IDE ports. The computer even freezes that way when a HDD is connected to the IDE without power (disconnected molex connector). I opted for a defective motherboard.
That's where it gets tricky.
I ordered a used ASUS A7V333 rev.2.00 motherboard on eBay, certifited as being tested and working properly.
I plugged everything in and whenever I pushed the power button, the computer starts for 2 seconds and shutdown, before the post. Nothing is displayed on the screen as the hardware doesn't even have time to start properly. Therefore, the problem is not software-related.
I then started isolate the cause of the problem.
I tried removing all the hardware except the original CPU (with properly connected fan) and the original PSU. Same pattern occured.
With only the CPU and the PSU connected to the motherboard (A7V333), I cleared the motherboard's memory. Still, the same shutdown after 2 seconds occured.
I took care of verifying that the motherboard is properly set to JumperFree mode to make sure it's not bad CPU frequency settings that cause the problem.
My parents have the exact same computer hardware (and their computer works properly) so I tried using their CPU and PSU on the A7V333 motherboard and still, the computer shuts down 2 seconds after I start it.
So, with only the CPU, PSU connected to the motherboard, tested with 2 different PSUs and 2 different CPUs, the computer continues to shut itself down after 2 seconds.
I'm running out of options. Could be a defective motherboard, but I'd be pretty unlucky to stumble upon 2 defective motherboards in a row.
Anyone has another idea before I throw everything out the window and order a new computer?