Question RX 6800XT stuck on VGA light/won't boot, but works fine when booted with another GPU

[grasmaaierjoey]

Hi there,
I recently built my first system and immediately ran into the problem of my newly acquired RX 6800XT being unable to POST as it would get stuck on the VGA indicator light.
I have since tried to try to boot with a single stick of RAM and swapping slots, different PCIe lanes and making sure the GPU is seated properly and receives power from the PSU; fans were spinning and GPU LEDs lighting up.
Additionally I have Q-flashed+ the motherboard to the latest version to rule out CPU incompatibility and possible bugs.
In all cases, the error would remain the same as aforementioned.
I have since bought a cheap GPU, an Nvidia GT 710, to assess as to whether the PCIe lanes were at fault; to my surprise, the system was able to POST without issues with this GPU installed, giving me obvious access to display and the ability to go into the BIOS, which has indeed been successfully flashed to the latest version (F13 for Gigabyte B550 AORUS PRO V2).
However, after seating the RX 6800XT in tandem, it simply would not appear in the BIOS as having occupied the PCIe slot, it fails to be recognized.
Having then installed Windows 10, the RX 6800XT could be detected after a simple connection to the internet and automatic driver updates, whereupon I installed the latest version of Adrenaline and now it functions normally, having done some 3DMark benchmark testing and finding no inconsistencies in performance.
Yet, even though it now shows up in the BIOS as having occupied its PCIe slot, I am still unable to boot the system without passing it through the Nvidia GT 710 first (setting its PCIe slot as primary for boot, without having any sort of display cable connected) as it will still get stuck on the VGA indicator light otherwise, nor does it allow me to enter the BIOS with the Nvidia GT 710 in tandem if the display cable is connected to the RX 6800XT, whereupon it will get stuck on the BOOT indicator light instead.
I have the strong impression that either the mobo or the RX 6800XT is faulty in some way, and am rather uncomfortable with the workable but hackneyed solution I've created, as I basically need another GPU for my GPU to function.

My parts:
CPU: AMD Ryzen 9 5900X
GPU: AMD RX 6800XT (and Nvidia GT 710)
Motherboard: Gigabyte B550 AORUS PRO V2
RAM: Crucial Ballistix 32 GB (2 x 16 GB) DDR4-3600 CL16
Storage: Western Digital Black SN850 1 TB M.2-2280 NVME
PSU: Corsair RMx (2021) 850 W 80+ Gold

Of course, I can rule out whether my GPU is at fault by trying it in another system, but I don't know anyone who'd be able to help me out, so I'd have to take it into a store.
I appreciate any comments, as in spite of gleaning the web for a solution, I have yet to find a freak situation such as mine, lol

 

[JohnBonhamsGhost]

I can rule out whether my GPU is at fault by trying it in another system, but I don't know anyone who'd be able to help me out, so I'd have to take it into a store.

ask around any friends, family, co-workers, etc that may be able to help.
there's always been quite a few computer "enthusiasts" at my places of employment, many you'd never suspect.

or call around to any local shops and ask if they're willing to help.
i've run into some that offer free diagnostics for certain hardware just hoping you'll continue to use them for paid services and products.