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Shutting down at random

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October 1, 2012 12:32:52 AM

I built this this thing

ASUS Sabertooth X85
i7-950 3.06GHz
Kingston HyperX DDR# (6)2GB
Corsair 750TX
AND
a pair of ASUS ENGTX 560 Ti GPUs

with the close support of the local Alpha Nerd;
it has been running this way for about a year, 15 months, suddenly it shuts off all unprovoked, then restarts itself;
ran fine for the rest of that day, no big load, just browsing, some Hulu, then shut down and then tried & failed, tried & failed, tried and booted up;
the next time it shut itself off, tried and failed, started but sent no signal to the monitors - WTH?!?

I pulled the lower of the GPUs from the MB, same problem; swapped that one into the upper slot and it ran fine with one vid card. Great. I installed the monitoring utility that came with the MB, thinking this was a heat problem, but that seems not to be the case: temps are between 40-50c, even if I'm playing Borderlands and watching Hulu.

NOW it has failed again, following the same pattern, all the way down to "VGA no signal"

The utility show everything green EXCEPT the 5v runs 5.5- 5.7 and spikes up to 6.2, and the 12v rail shows about 14.

Now I'm afraid to turn the damned thing on at all, and I fear I may already have cooked both of those very expensive GPUs.

Mayday! Mayday! Any help or advice would be most welcome.

More about : shutting random

October 1, 2012 1:40:20 AM

Did you at any time overclock your GPUs?
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a c 87 B Homebuilt system
October 1, 2012 2:05:20 AM

Sounds like a bad PSU - do you have a multimeter? Motherboard readings are generally pretty inaccurate.

Corsair is usually pretty good, but nobody is perfect and you might have one of the few dead ones.
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October 1, 2012 2:08:55 AM

knightdog56 said:
Did you at any time overclock your GPUs?

No, I did not; I'm really not that bright.
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October 1, 2012 2:12:27 AM

Someone Somewhere said:
Sounds like a bad PSU - do you have a multimeter? Motherboard readings are generally pretty inaccurate.

Corsair is usually pretty good, but nobody is perfect and you might have one of the few dead ones.

I do, & that's tomorrow's agenda. D'ye reckon I should unplug everything and read the plugs direct, or have I got to fire the thing up & backprobe everything? For, you know, loaded readings?
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Best solution

a c 87 B Homebuilt system
October 1, 2012 2:19:34 AM

You need to have it at least sitting with the computer on and at BIOS, or there won't be any voltage to read. The motherboard tells the PSU when to turn on and off.

You want to look at the voltage from black-yellow (12V), black-red(5V), and black-orange(3.3V). Don't worry if they aren't exact, but they should be within 5%.

If it gives you a negative reading, you've got the probes the wrong way round, but the answer is the same.

EDIT:You can stick the probes in molex connectors for all but 3.3V, which is easier than getting to the 24pin plug usually
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October 2, 2012 6:09:32 AM

So
I opened it up, disconnected everything, jumped pins 15 & 16 so that the PSU would run, and tested everything with the multimeter; everything nominal: 12.35, 3.41, 5.11, very consistent. Pin 14 showed <12.15>, but all the other values were the same, not just on the 24-pin, but on the peripheral leads as well.
Stuck both GPUs back in and, with the box laying on its side and open, fired it up, no prob, Bob. Plugged a spare monitor into it, nothing, changed sockets - success!
Short lived. Moved it over to the desk, hooked up the usual suspects, and got the same results as before.
BAH!
At least I have demonstrated - I think - that it isn't the PSU.

Any other ideas? And why the hell would orientation make any damn difference?
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October 3, 2012 4:00:17 AM

Make sure all the screws that hold the motherboard in place are snug, do not overtighten. With case orientation on its side and everything works it could be a cracked motherboard trace, but just check the screws first.
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October 11, 2012 3:29:20 AM

Someone Somewhere said:
You need to have it at least sitting with the computer on and at BIOS, or there won't be any voltage to read. The motherboard tells the PSU when to turn on and off.

You want to look at the voltage from black-yellow (12V), black-red(5V), and black-orange(3.3V). Don't worry if they aren't exact, but they should be within 5%.

If it gives you a negative reading, you've got the probes the wrong way round, but the answer is the same.

EDIT:You can stick the probes in molex connectors for all but 3.3V, which is easier than getting to the 24pin plug usually

Well I finally broke down and swapped in a new PSU, and now all the telltales are green and stable. That's what I get for truting my own measurements!
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October 18, 2012 1:33:05 AM

Best answer selected by bathead.
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!