Aside the fact that you are way behind the updates, and considering that you know that from BIOS to Grub to the desktop, the GPU ports are activated in this order:
VGA > DVI-I > DVI-D > HDM I> Displayport
You can create a fixed layout for your screen and monitors and save it in /etc/X11/mhwd.d/nvidia.conf
Here is an example that might help you
Read along to get the context.
In some cases seems that enabling early KMS helps too, see here: