[Help] Reboots during intensive tasks

[lewisx6]

I've been having this problem since I first built my system a few weeks back. When I'm doing something intensive like gaming, gpu stress test or cpu stress test - actually those are the only things to cause it so far - my system will automatically reboot, but it takes a minute or so between shutting down and actually booting up again. My measurable temps are a little high but definitely still safe and would not cause a thermal shutdown. Both my CPU and graphics card stay at around 75c under full load, though the CPU is only ever that during the stress test. My PSU is only a little warm to the touch when it happens too, nothing out of the ordinary.

Specs:
CPU: i5-3570k with Contac 21 cooler (stock settings)
Graphics: VTX 7870 Tahiti LE (stock settings)
Motherboard: MSI Z77A-G43
PSU: XFX XXX 750W
RAM: Kingston HyperX 2x4GB 1600MHz

I think I have it narrowed it down to three possible things (could I be missing anything?):
Chipset overheating which I can't monitor
PSU over or undervolting components
Dodgy motherboard

I figure I can only find out if it's the mobo through process of elimination, the chipset I'll know more about tomorrow when my new fans arrive and I improve my cooling, so that just leaves me with the PSU for now and I need a way of logging voltages. I have HWMonitorPro but it doesn't save logs if the systems shuts down unexpectedly. Keeping my eye on it can't really be done either because it'll only be a split second before it shuts down. Are there any other options that don't involve a multimeter?

 

[Onus]

I'll go with "dodgy motherboard," based on https://spreadsheets.google.com/spreadsheet/pub?key=0AgN1D79Joo7tdE9xMUFlMEVWeFhuckJEVF9aMmtpUFE&gid=0 (even though that's a listing of AMD boards) and a lot of stuff linked at http://www.overclock.net/a/about-vrms-mosfets-motherboard-safety-with-high-tdp-processors
MSI is just not in the same league as Asus. If at all possible, improve your case cooling; make sure you have good airflow through your case.

 

[lewisx6]

Thanks for the reply. I took out one stick of RAM and during a GPU stress test it restarted as usual, but then I swapped that stick with the one I previously removed and now something very strange is happening. I ran the Kombustor again but this time it seemed to work fine, right up until I pressed ESC to exit full screen which cause it to restart. It has done this 4 times in a row now. I don't know what to make of it.