Bad TX750W, or mobo?

[Crisco]

I recently built a PC and am having problems with it locking up at the bios screen, and/or suddenly shutting down. I believe I've narrowed the problem down to either the PSU or the motherboard (ASUS P7P55D Pro) and am looking for guidance.

 

I have a Corsair TX750w (model CMPSU-750TX) I used a voltage tester (Coolmax PS-124) and when I check the 24pin connector, the -5V LED does not light. Does this mean it's a bad PSU?

 

The problem first started when I was playing Guild Wars. This was after the computer had been running for a few hours (fresh install of XP 32bit) with no problems. Suddenly the machine shut off and rebooted. Initially I thought it was a heat issue, but after reapplying Arctic Silver (a few times), I was able to get the CPU temperature down to about 30C (it was up around 48C before that). Yet still the crashing continues.

 

At first the crashes would only happen after 10-15 minutes, and only if I was doing something computationally demanding. Now, it even freezes at the BIOS screen within just 2 minutes.

 

Any ideas? I don't want to exchange the PSU if there's no problem with it, but I'm out of my depth when it comes to details about voltages, etc.

 

Thanks in advance,

 

-Chris

[Wired]

The -5V line hasn't been part of the ATX spec in over 5 years. It's supposed to be missing.

[cmdrdredd]

Do you know anyone or do you have another PSU you can temporarily plug in for testing? Also remove any non-essential items from the motherboard and test. If it works, start plugging things in 1 by 1. Just a note, my USB Keyboard locks up my BIOS as well, but when it's removed startup is about 30sec. I can safely plug it back in at windows.

[Yellowbeard]

You can also try this short test to see if it gives you any insight as to what the PSU is doing.

 

http://forum.corsair.com/forums/showthread.php?t=63991