I recently have started to use Blender and made the project a lot of people have the one with napkin the glass cup. I rendred that with my CPU(I7-490K if that matters) and as expected it took some time. I also have a GPU in my computer GeForce GTX 970 and when I tried to render with that all i got was the blank grid screen and no render or sign of starting to render. In my user prefences I already have my compute device set to CUDA and the 970 selected and in the render section I have also set the device to GPU these settings get me to a blank grid screen. How do I fix this so i can render with my GPU.