I noticed with a recent update of my Nvidia driver, I no longer had the option to render with GPU. On checking the User Preferences–>System, there was no CUDA capable GPU found! On doing some checking around, I downloaded the latest CUDA Toolkit install and that seemed to do the trick. Not sure if there is an easier solution.
I’m using an Nvidia GTX 970, driver version: 353.90
CUDA Toolkit download: https://developer.nvidia.com/cuda-downloads
Warning: download is HUGE
Just wanted to post this in case someone else runs into same issue.
//Dan