Due to an error (probably me) the .cubin files that come with the latest Rhino WIP release (2017.05.02) are incorrect. I have already fixed the files for our build system, and hopefully @brian can update the public installer soon.
Until then if you already downloaded and installed the latest public Rhino WIP you can get the correct .cubin files and place them in the right place to ensure switching to Raytraced with a CUDA (Nvidia) card works as it should.
Please download the 7z file containing proper .cubin files from my dropbox. The contents of the 7z file should be placed in
C:\Program Files\Rhino WIP\Plug-ins\RhinoCycles\lib (you’ll see that the current files are all 1KB or smaller).