Certain bosses, screen sleeps, PC then freezes/crashes

[Khuteh]

Hi all, i've a little problem i was wondering if anyone has had similar issues or has ideas what the issue might be..

I have a pretty good pc, bought brand new november, gtx970, i54790k, 8gb vengeance ram, hero mobo.

On certain bosses/fights my screen sleeps, then a few seconds after the pc will die/crash/stall. It still whirrs but i have to hold power to shut it down. (I can hear mumble still when screen goes black then it goes also after 3-4 seconds)

99% of the time it's ace, everything on ultra (incl raids), plays great, superfast, no lag etc, but on:

Tectus (2 or 3rd transition)
Blackhand (phase 1 to 2)

and now Iskar and Xhul.

I've tried lowering graphics settings, i've played with nothing else open, but i keep getting this issue! Any thoughts?

Possibly:

Mobo
PSU (power fluctuations)
other..

[Nuckels]

Sounds like overheating/dieing gpu to me, dxdiag please + a picture of your temps with hwmonitor " http://download.cpuid.com/hwmonitor/hwmonitor_1.27.zip " WHILE running WoW in a raiding enviorement.

[Khuteh]

Sounds like overheating/dieing gpu to me, dxdiag please + a picture of your temps with hwmonitor " http://download.cpuid.com/hwmonitor/hwmonitor_1.27.zip " WHILE running WoW in a raiding enviorement.

Thanks for the reply, i will try and do this tonight in LFR, as raiding tomorrow i want to try and feex eet!