XPS 8930, BIOS, cannot disable Intel UHD Graphics 630?

As you have found, there is no option to disable the integrated/onboard graphics. The integrated graphics is automatically disable when a graphic card in installed.

Thank you for your message. This system does not have the option to change the graphic card in BIOS. The system will switch automatically between the two cards based on the application used.

There is an option to manually open an application with the Nvidia card & that needs to be done on the Nvidia control panel.

You will either need set the game to open with Nvidia by default in the Nvidia control panel or disable the Intel card in device manager.

Is there a way on the BIOS to stop the computer reserving 16GB of my 32GB RAM on Shared GPU memory when the system includes a dedicated GPU?

I am not aware of a way in the BIOS to stop the computer from reserving shared GPU memory. I am not sure you would want to do that since both the integrated and dedicated graphics uses shared GPU memory. If you are not using the Intel HD Graphics it should not be using any memory resources (see my Task Manager readings below). In addition, reserving 16GB of memory does not mean that it is not available to be used for something else; if you look at the Memory used in Task Manager you should see more than 16GB available (I have over 20GB available).

The Task Manager image you posted is showing the dedicated GPU (GPU 0) and not the Intel HD Graphics. I assume that Task Manager is not showing your Intel HD Graphics is because it is disabled. When I look in my Task Manager the Intel HD Graphics (GPU 0) is showing Utilization of 0%, GPU Memory of 0.0/16.0 GB, and Shared GPU Memory of 0.0/16.0 GB. My dedicated (NVIDIA GeForce GTX 750 Ti) GPU (GPU 1) is showing Utilization of 6%, GPU Memory of 0.8/18.0 GB, Dedicated GPU memory of 0.8/2.0 GB, and Shared GPU Memory of 0.1/16.0 GB.

You're mis-interpretting that data.

It's actually saying up to 16 GB out of your total of 32 GB of system RAM can be shared with Intel UHD Graphics, but that's only if/when actually needed. It's not saying 16 GB of system RAM are totally reserved and only available to UHD Graphics.

The data you boxed says 0.1 GB out of a total of 15.9 GB of sharable system RAM was actually being used by UHD Graphics at the time you took that screenshot. So less than 1% of the total amount that potentially could be shared with UHD Graphics was actually being used by UHD Graphics, not that those 16 GB could only be used by UHD Graphics.

My XPS 8930 has 16 GB of total system RAM. Task Manager shows that 7.9 GB of system RAM can be shared with UHD Graphics. So comparing your info with mine, that suggests Win 10 defaults to allowing ~half of the total installed system RAM to be sharable with UHD Graphics.

Don't know how much sharable RAM UHD Graphics might use on your PC if you're watching a vid or gaming. On mine with a Dell OEM GTX 1660 Ti video card (6 GB of onboard RAM), Task Manger shows that UHD Graphics is using 0% of sharable system RAM while playing an .mp4 vid, while the add-in video card is using ~20% of its own RAM, and 0% of sharable system RAM while that same .mp4 is playing.

If letting UHD Graphics use a fraction of sharable system RAM bothers you that much, you could could click Disable Device on the Driver tab for UHD Graphics in Device Manager. IDK if there might be situations and consequences if/when some activity requires UHD Graphics and can't use the add-in video card, so keep that in mind.

FWIW: The onboard video ports are not disabled when an add-in video card is installed in an XPS 8930 with a Gen 9 CPU. True, you're supposed to connect the first monitor to the add-in video card, but the onboard ports still work even if no monitor is connected to the add-in card...