I had to install the CUDA Dev kit () in order for TFD to use my Quadro K4000M. Before installing that, the GPU wasn't available for simulations. And it seems that not all nVidia cards that contain CUDA cores are compatible with the latest version of the Dev Kit (7.5 - ).

CUDA driver version is insufficient for CUDA runtime version Ubuntu 14.04.3 GTX 970 CUDA 7.5: CUDA_driver_version_is_insufficient_for_CUDA_runtime_version.txt Explore Channels Plugins & Tools Pro Login About Us.

But if you read other forums either for Lightwave or other Cuda rendering threads elsewhere, most recommend having two GPUs available for rendering, with one dedicated to TFD for simulations and the other to continue using as your primary GPU for other software. I only have one, so if I try to simulate using the GPU and then attempt to do other things like using Office or Adobe products, the simulation crashes occasionally and overall Windows interactivity slows down. How to turn off focused in outlook for mac.

This is due to the GPU trying to simulate AND process desktop functionality at the same time. In your case, the GTX 660 is supported by CUDA 7, so it would be the one to use for TFD. The FX 1800 is on the Legacy page (), so that would likely remain your primary GPU. I realize your post is from 6 months ago and your system config may have changed since then.

BTW, I haven't looked to see if there is an older CUDA installation that would support legacy GPUs.