Black screen while gaming

[xelerondd]

Hello,(I apologize for my bad english)
I have an XFX radeon 7970. And it goes in a black screen moment it crosses 70 degreesish. The screen goes black but the PC is still on because i can hear it and lights n stuff are on but can't do anything. and i have to manually restart. Just assembled the PC around 2 weeks ago. Drivers are all up2date. The ventilation is all good. For the first week it worked fine. I tried running MSI stress test and it reboots after it hits 65-70 degrees too. Any Help guys?

 

[popatim]

It goes blank the moment WHAT crosses 70 degrees?

If its the cpu then check the heatsink and thermal paste application.
If its the GPU then return it. it should run well into the 80's without an issue.