Built a system with an A8-5600k, Biostar A85W 'Hi-Fi' motherboard, G. Skill ripjaws RAM, an 800W PSU and running Win 7. This is probably my 6 or 7th build, not exaclty a newb on proper build practices including thermal paste application, grounding, etc...
Was running a Leap Motion controller and the 'flocking' application, which I believe to be somewhat processor heavy (lots of real-time fish movement processing going on). I was running two monitors through the APU, one through VGA the other through HDMI. At one point after about 5 minutes of 'flocking', the monitors just shut down. Done. Manually shut the computer off using the power button, waited about 10 minutes, fired back up and the monitors came alive again for about 4-5 minutes, then shut down. Both of them. After that, couldn't get the monitors on again. Best I could tell, everything else was firing up correctly.
First attempt at troubleshooting was to install a dedicated ATI Radeon 6450 - not super powerful but should have been plenty for my application. It seemed to solve the problem for a few days, then poof, monitors just shut down again in the middle of running an experiment after flocking was running for about 4-5 minutes. Couldn't get them back even after cooling down for a day.
Next though was motherboard, swapped the Biostar out today for a Gigabyte A88X board. I'll admit that I didn't reapply the thermal paste to the CPU, but I've only had this system about 2 months now the paste looked fine, felt like a nice seal when I put the CPU fan back on. First tried through the integrated graphics ports, one monitor only, tried all 3 ports (VGA, DVI and HDMI). System spins up, but no monitors come on: 'no signal' floats around the screen. Tried again with the 6450 card, still no monitors come on. I can't imagine this is a CPU overheating problem because the system's not on long enough for it to heat up.
I've also tried 3 different monitors now, just to be systematic. My next thought is going to be CPU, but before I go and swap that out (and pay yet more for what was supposed to be a budget build), wanted to get other's opinions. Do I go after the CPU next, or can you suggest something else? Note that asking about temps or BIOS settings won't be helpful since I obviously can't access them without monitors.
Thanks in advance.