Mobo reporting bad voltages

[HellFyre]

My system has been running fine for over a year now (P4 2.6, 2GB RAM, GF 5700U), up until last night when it wouldn't stay running for more than 10 minutes before completely locking up - sometimes with screen relics.

So I loaded up the motherboard monitor to see if maybe I'm overheating (no OC'ing) since I've been playing HL2 lately. Nope, but I did notice that the voltages were way outta wack. I rebooted to the BIOS to make sure the responses were accurate, and this is what I was seeing:

3.3 = 2.7
-5 = -5
+5 = 5
-12 = <blank>
+12 = 11.0

At least these are the numbers I remember off the top of my head. The -12 was blank and the +12 was way off, as well as the 3.3 (maybe the 5, but I'm pretty sure the 3.3, I can check later if the difference is relevant)

My immediate thought is the power supply, because of the numbers and the fact that this was the only part I skimped on.

Would you guys agree? Or are the voltages above measured after the motherboard regulates, implying that the motherboard is bad?

[Sane_Man]

I would turn the system off for a few hours to cool off, then check the voltages again. Also, clean the huge dust bunny out of the PS fan.

[HellFyre]

Oh. I hadn't thought of dust build-up (which is most surely there) causing voltages to be off. What about the blank -12? I've never even seen that before. If is was truly nothing, how did the system boot?

[Gragorin]

THe -12 rail really isn't used anymore AFAIK. I'm pretty sure that it comes up blank on my PC too. I would suggest that the power supply be voted upon as being the likely candidate for the problems that you've been having.

[donoman]

You can check your power supply with a nice loading resistor across the 5V line (to ground) and a voltmeter. Use a 10W loading resistor of 2Ohm

[donoman]

Or an 1157 Light bulb from 5V to ground. :) Actually I've only done this on AT power supplies. I think there's another connection you need to make (but it's easy). They also sell something like this at Fry's so you can check yo shite.

[HellFyre]

Well, I'm 'borrowing' a p/s and voltmeter from work. (Sad that I don't already have one.) I'll measure the voltages from the power supply. If they reflect what the BIOS says, out goes the p/s.

[HellFyre]

I threw in a newer, higher quality, bigger wattage power supply last night. Everything seems to be ok now, but I'll let a few days of HL2 determine that. :geek