G5 15 5590 GPU Over-Ruled by Intel UHD Graphics

On most laptops with dual GPUs, even many gaming-oriented laptops, the built-in display and most or often all of the display output connectors are physically wired to the Intel GPU.  The NVIDIA GPU exists as a "render-only" device that activates when needed (or when forced to run using the "Run on graphics processor" option in the right-click menu of an application shortcut), and it then passes completed video frames to the Intel GPU for output to the display.  This technology is called NVIDIA Optimus, and it has been around for quite a long time.

The main reason for this design is battery life, because when the NVIDIA GPU isn't connected to any displays, it can be completely powered off when its performance isn't needed.  By comparison, if it had direct control of any display outputs, it would need to remain active whenever a display was connected to that output, even if nothing graphics-intensive was going on.

It sounds like on your particular system, the output you're using for the external display might be wired directly to the NVIDIA GPU.  Some gaming and workstation-grade laptops do that because there are certain technologies that the Intel GPU doesn't support passing through and/or that require an NVIDIA GPU to have direct control of the display output.  These technologies include VR, G-Sync, Adaptive V-Sync, stereoscopic 3D, and (on many systems) 5K resolution.  Since some gaming laptops are specifically designed to support VR, they need to have a display output wired to the discrete GPU.  However, on some gaming laptops only the HDMI output was wired that way, with the USB-C output (which can carry DisplayPort) still wired to the Intel GPU.  That's fine if you're using a VR headset that uses HDMI, but if you have something like an Oculus Rift S or Valve Index that requires a DisplayPort signal, you would be stuck.

Finally, there are some systems that offer a BIOS option that allows you to choose which GPU has control of the built-in display and/or the display outputs, but the only Dell systems I know of that offer this are the Precision 7000 Series models from the 7x20 onward, because they use a more complex and expensive motherboard design to allow this flexibility.

So yes, disabling the Intel GPU will prevent your built-in display from working, along with any displays attached to display outputs that the Intel GPU controls.  But it's also perfectly fine to keep it enabled.  The NVIDIA GPU should still become active when needed, and if that doesn't happen automatically, you can either set up a profile for that application in NVIDIA Control Panel to force the NVIDIA GPU to engage when you run that application, and/or use the "Run on graphics processor" menu option I mentioned earlier.  I would not recommend keeping the Intel GPU disabled, because if you disconnected your external display while your Intel GPU was disabled, your built-in display would not light up in order to let you see what you were doing.

Alright!

Thank you so much for responding so promptly. It is useful to know this information I will keep!

Thank you!!

You're very welcome. I'm glad you found it useful.

Thanks for the comprehensive answer, I've just been searching around regarding a similar issue on my G5 with Nvidia RTX2070, it does probably explain why I still see Intel GPU usage when forcing my Nvidia GPU to operate on certain applications.
Cheers.