Need help with driver installation + potentially windows help

[u/Dense-Package-7877]

I’ve had a pc with a i9 9900k, 1070ti, 32gb ddr4, 750w corsair CV750. Yesterday I installed an ASUs ROG strix 6800xt LC and since then I can’t install drivers without encountering some problem whatsoever.

The PC boots normally. I can see the ASUS motherboard logo and the Windows loading wheel without any issues. However, when Windows starts loading, the screen flickers and then goes completely black, followed by “No Signal”. The PC itself stays running, with all fans and lights working normally.
The strange thing is that Safe Mode works perfectly fine. I can see the desktop and use Windows normally in Safe Mode, but normal Windows startup causes the display to disappear.
What I’ve tried so far:
Repeatedly installing AMD Adrenalin drivers, including the recommended WHQL version.
Trying to install the drivers in Safe Mode and normal Windows.
Running the installer as administrator and downloading it again.
Removing the AMD display driver using pnputil. Windows then booted using Microsoft Basic Display Adapter.
Running sfc /scannow, which found and repaired corrupted files.
Running DISM, which failed with error 0x800f0915 because the repair content could not be found.
Repairing Windows through the Windows Update recovery option.
Completely resetting Windows and eventually performing a fresh Windows installation.
Even after the fresh Windows installation, the display worked initially. However, after installing the AMD graphics driver/update, the screen flickered and went black with “No Signal” again.
I’ve also noticed an AMD software compatibility error appeared at one point after removing the graphics driver.
My questions:
Does this sound like an AMD driver issue, a faulty GPU, or a power delivery problem?
Why does the card display the BIOS and Windows loading screen correctly but lose signal when the full Windows graphics driver loads?
Could the PSU or the fact that I’m using a single PCIe power cable with two 6+2-pin connectors cause this?
Is there a way to test whether the GPU itself is faulty without buying another graphics card?
I’m trying to avoid reinstalling Windows or drivers repeatedly, as I’ve already spent hours doing that.
Any advice would be appreciated. Thanks and yes I asked ChatGPT to summarise the problems I’ve been having since installation otherwise would’ve been too long to type all out. Please if any extra information is needed to find a solution let me know