Which GPU(s) are you using and how did you install PyTorch 1.6.0?
If you’ve installed the conda binaries or pip wheels, your local CUDA installation will not be used, but binary (or wheel) will ship with their own CUDA, cudnn, (NCCL etc.) libs.
Good to hear you can install PyTorch 1.3.1 with CUDA10.0, but that’s not a proper solution as you would be missing all the new features and bug fixes.