, thanks for answer.
Actually, I thought the same for the first time, but I ran several OpenGL games and benchmarks, repeated today and they go excellent...
* Unigine Heaven 2.0 in both DX11 and OpenGL modes
they are hard enough judging from fan rotation... no problem.
GPU temperature was up to 88'C but no issues.
Also I ran Serious Sam TFE HD (switched to OpenGL renderer)
factory demos and /benchmark() from console
- all clear and GPU temperature was not more than 55'C
looks like this Sam is too weak for nowadays cards...
DirectX and GPU (CUDA/OpenCL) benchmarks as well:
* 3DMark 11 and 06 today worked without driver shutdown.
* OCCT Perestroyka 4.2 - all clear...
* Fluidmark (for PhysX)
Looks like lowering system timer from 1000 HZ to 100 HZ can be the solution!
no squares now for 20 minutes...
Well, it does not solve the problem, just decreases the frequency of its appearance...
Still looking for demonstration to warranty men. It would be ideal if the card could develop its defectiveness and silently die without smoke.
Tomorrow wil check it in another Linux computer...