Limit GPU utilization of Jup Notebook to e.g. 80% possible?

Does anyone know if it is possible to max GPU utilization (e.g. to 80%) when training a model in Jupyter Notebook with PyTorch? (not memory)

On Ubuntu 18.04, training hogs 95+% of the GPU performance and my PC (single-GPU) becomes barely usable. I rather have the GPU leaving like 20% for the system and train a bit slower, so I can continue doing stuff like browsing and programming stuff only requiring CPU.