ClojureCUDA now supports the latest CUDA 9.1. That should eliminate the trouble of downgrading your CUDA installation to CUDA 8. If you install the latest CUDA toolkit, everything should work smoothly. If you have CUDA 9.0, it will work. I am not sure about CUDA 8 - even that should work, but I haven't bothered to try it, since by now CUDA 9 is what most people install by default.

Of course, CUDA 9 is also suported in Neanderthal.