on my machine the problem just disappeared without any (known:)) changes from my side.
I did thousands of renderings with cycles on the gpu and everything worked fine now..
Very strange, keep my fingers crossed.

The exact same problem is back again. Was a few days away from my machine. Today try to render in cycles:
Problem back exactly as described above.
Re-installed all nvidia drivers: no success, problem stays. cuda-z shows no problems, just works fine

What I did

1. Run cuda-z on unchanged pc - successful. No problem (strange)
2. removed all nvidia drivers
3. Installed all nvidia drivers as fresh installation
4. Run Blender, changed from blender render to cycles render. Rendered an image>sucessful

ok thnx. will do that tomorrow as soon as i have access to that machine.
I will also install and try with cuda-z
I use Touchdesigner heavily on that machine, and that works well. And TD make massive use of the graphics card.

seems somehow related. problem description identical

ok i will do that. have access to that pc tomorrow.
It happens with a GeForce 1080. I have 2 other PCs with other Nvidia cards and there evrything works fine.