Solved by vfdev-5 in post #2 
              
              
                On MacOSX (without CUDA support) it is 
>>> import torch
>>> torch.cuda.is_available()
False
>>> torch.cuda.device_count()
0

either you can check it with CUDA_VISIBLE_DEVICES="": 
CUDA_VISIBLE_DEVICES="" python -c "import torch; print(torch.cuda.is_available() + torch.cuda.device_count())"
0