Dear forum members,
On my new Windows 10 AMD Ryzen system I wanted to go for a pure python (non-Anaconda) based pytorch install, since I didn’t get numpy to work well with openblas on Anaconda.
So I created a fresh virtual environment, first installed numpy and then installed pytorch by running
pip3 install torch===1.3.0 torchvision===0.4.1 -f https://download.pytorch.org/whl/torch_stable.html

The installation finished but when importing torch I ran into the error
from torch._C import *
ImportError: DLL load failed: The specified module could not be found

I tried installing the cpu-only version of torch which had no issues.
I was finally able to fix the error on the GPU-version of pytorch by installing CUDA manually before installing pytorch. (again by running pip3 install torch===1.3.0 torchvision===0.4.1 -f https://download.pytorch.org/whl/torch_stable.html)
This confuses me as it was my understanding that pytorch brings it’s own CUDA and cudNN which are independent from the system’s CUDA installation.
So I would like to understand how installing CUDA could have fixed my problem?
I would be grateful for some insight into this behaviour, as I would like to understand how my pytorch installation is configured.
Thank you,
Paul