1. Gainward support replied
Thank you for your request.
We are confident that this problem has nothing to do with the GTX580 Phantom 3GB in the first line. Since the time of selling this graphics card, we never had any known problem with it; this may also be related to the used operating system. This issue is related to the NVIDIA driver and can therefore only be solved by them, because they are publishing all drivers.
Anyway, we will forward this problem to NVIDIA.
at SuSE forums
checked another card received as replacement, but no luck:
produced the artifact again on this new card in less than half an hour
So we should wait for solution from NVIDIA.