if someone is interested in investigation: kept the nvidia driver and openGL libs as they are unified drivers for all nvidia GPUs changed the Graphics Adapter from nvidia GF 8500 to GF 6200 (and therefore back from DVI to VGA mode and modelines) Heureka! The game runs fine and frame rate is still reasonable. The onboard GF 8200 GPU is off ? (according to the Xorg.0.log) (EE) NVIDIA(GPU-1): Failed to initialize the NVIDIA graphics device PCI:2:0:0.
