You might wanna take a look at this post as a starting point, it is more laptop-related but the Nvidia hardware issue you are describing appears similar to “Part B: Fix NVIDIA GPU Hang on Resume” in this guide.
Always make sure to do your own research and take precautions before making any changes. I have not tested any of this.
Alternatively, you can always just disable sleep and just use shut down. If on idel for longer periods…put on a power saver profile and turn off monitor, I guess.
Until there is proper open-source firmware for nvidia drivers…this issue is likely to remain. Sorry about that. 
Maybe someone else has other possible fixes/suggestions.