Problem installing RTX 2080 Ti GPU, code 12, I/O conflict, IRQ conflict

[Bootlengin]

I have an HP Elitedesk 705 G4 that I received second-hand and am having a critical issue when installing a GPU. It would appear that there is a conflict between my GPU (RTX 2080 Ti) and APU (Ryzen 2200g) causing the GPU to display code 12 from device manager. I have never in my life come across a PC that had so much trouble accepting a GPU. In fact, I've tried two different 650 Ti boosts, a Titan Z, and a 680, but all of them behave the same way as the 2080 Ti in this particular PC. 

The external GPU is being powered by a 1300w EVGA PSU externally.

Here are some things I've learned while diagnosing these last couple weeks:

0) the Nvidia driver gives me a code 12 in device manager.

1) the GPU isn't being assigned an IRQ.

2) Nvidia control panel crashes before even trying to load.

3) nvidia-smi throws out "failed to initialize NVML not found".

4) 0000000c CM_PROB_NORMAL_CONFLICT in dxdiag (the card name is "Microsoft basic display driver" while the manufacturer is "NVIDIA"' which makes no sense.)

5) when looking at the generic PnP Monitor in device manager, it shows that it's using the "Microsoft basic display driver" through the GPU, even though the Nvidia drivers are installed and "active" ( though not really since the Nvidia driver is throwing a code 12) and the video bios is set to "nVidia BIOS-P/N@N13278(90.02.30.40.7E").

6) After rebooting from an instance where the GPU is "working", usually the VGA boot device gets defaulted back to the AMD VGA controller and the integrated graphics switches itself back on and won't let the nvidia GPU get detected again until I do a complete bios reset.

7) dxdiag shows that the display device has no dedicated memory.

😎😎deinterlace caps show up as empty shells in dxdiag.

And here are some things I tried that didn't work:

1) using DDU to uninstall both AMD and vidia drivers, then reinstalling Nvidia drivers in safe mode.

2) doing a complete bios reset by unplugging everything, removing the battery, and discharging the caps with the power button (though this did get the GPU to activate in post a few times, albeit with extremely crippled functionality and drivers failing to load. In fact, trying to launch any game with the GPU active in this crippled state results in errors being spat out saying that my GPU is incompatible with openGL.)

3) installing the latest chipset drivers.

4) updating bios to 2.22.00 Q16.

5) uninstalling/disabling the APU drivers.

6) in bios, disabling the APU graphics and setting the Nvidia GPU as primary. (This does nothing because the bios automatically defaults back to the APU and turns integrated graphics back on all by itself after rebooting from the bios screen.)

And here's some possibilities that might be causing the problem:

1) The bios is malfunctioning and isn't properly switching off the iGPU while giving the external GPU the resources to function.

2) the PC doesn't like the fact that I'm using an external PSu to power my GPU.

3) the drivers are installing corrupted, causing it to throw out errors and not load properly after reboot.

There was a single point in time a couple weeks ago where I was able to get the GPU to work properly and I was even able to do a superposition benchmark where I was able to get a score of 22000-ish at 1080p extreme (I was able to get a pretty stable 60 fps). Unfortunately, after I rebooted, the GPU stopped working properly again. And now it's driving me nuts that I cant remember how I did it.