ASUS Sabertooth X85
Kingston HyperX DDR# (6)2GB
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.
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.
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?
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.