Crisis situation! Diablo 3 comes out in 3 days and my wife's computer is not behaving. It will randomly after a few hours of use simply shut off. Not entirely off, the power LED will stay on and the HDD activity light will blink, and a fan in there is going but that's it. It's done this before, around last November or December. I thought it might be heat related (Speedfan was showing a couple sensors at around 65-70C, which isn't super hot, but hotter than mine which is identical mobo and CPU runs by a little bit), and ended up replacing the CPU fan and heatsink and redoing the thermal grease as it had been stock. Nothing fancy, but it seemed to have done the trick. It's doing the same thing again.
I've blown all the dust out, and checked for bad caps while I was in there. I tried replacing the PSU the other day, which I thought had worked since it had been stable for a couple evenings of Netflix and gaming, but it just did it again a bit ago. I can't find anything in the event log other than Windows complaining the previous shutdown had been unexpected. According to her it seems to do it most often when loading zones in Tera, which does jive with the one just experienced (though it was loading a zone in Path of Exile) which makes me think it might be the HDD. SMART seems to check out (at least according to Speedfan. I'm currently burning a UBCD to check and see what their tools say.)
edit:UBCD's drive diagnostics also checkout. Running Memtest for shits.
If it's not that, I'm in for a headache. It's currently got this
mobo, which isn't exactly a spring chicken, anddoesn't support DD3, so if have to replace that or the CPU, I'm going to have to practically replace half the system.