I wrote to the supprt.
I did really everything. Used the driver your troubleshootpape suggests and everythingelse I found in the forums.
I had like 3.5 GB free vram and got crashes all the time after 10 or 20 rendered pics.
Really, i can´t understand why something like this can happen. I have to finish the job, canceled my vacation because of this. Worst, worst userexperience i ever had with a software = (