Solved by el_youssfi_azeddine in post #2 
              
              
                GOOD luck man, I just passed one week to try to fix cuda (rtx3090). Finally I followed this tuto: Installing Pytorch with CUDA support on Windows 10 | by Eugenia Anello | Towards AI 
I used cuda 11.0 
pytorch: 1.7.1 
and it works good now!