Use integrated GPU for monitors, NVIDIA for cuda calculations (linux desktop)

I have installed linux debian 10 testing on my desktop. In the installation process, I was using one monitor connected on iGPU, not on NVIDIA.

After the installation, I cannot boot on my OS using the iGPU, only via NVIDIA card. But, I want NVIDIA only for deep learning and not consumes resources for the monitors.

It would be great if you can guide me through this.