Vertical lines crash only when gaming

[Dogoid]

I5 4690k
2x4 Corsair Vengeance RAM
Gigabyte-Z97p-D3
MSI 7970 OC TwinFrozr
Windows 8.1
Antec 750 HCG

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In the last day I have had my PC crash with some graphic artifact like this https://i.sli.mg/xSQBab.jpg with some sound looping.


This , i noticed happens just as the GPU fans start to spin up.
I Tried my integrated graphics, and all went well, so i removed the card and stuck it into the 8x PCI e slot, same thing.


I downloaded Furmark and decided to monitor the GPU stats, it crashed the same way within 10-20 seconds, again noticing the crash followed the spin up of the cards fans.


I decided to look at the temps, and noticed the temps go from 39c idle to 60+ within 5 seconds and the crash happens around 71C.


SO It's surely temp based but what i don't understand it, I have had this card running at 80C gaming and it be fine, but it seems to me thermal protection is kicking in but at a lower temp i'm used to game at without issue in the past.


Does the rate of temp climb factor in too amongst the actual temp for thermal protection?



I noticed the heatsink is a bit dusty , some clumps on the edge, but i'm thinking maybe add new thermal paste.
What you think?

 

[Dogoid]

This is what I've been doing this afternoon.

I have been experimenting with under clocking to reduce temps with Afterburner, I have underclocked core voltage and core clock and manual fan at 100% , I have managed to keep the system stable in gaming as long as it's under 70C, this of course is at the cost of FPS but at least i can game somewhat without it crashing.
It's odd that when it gets to 70-71C it crashes , when GPU's can handle temps much more than that.
Also when settings in Afterburner are at stock/auto when i game the temps go from idle 37C to 60C in 2 seconds