Replacing nVidia card with AMD Radeon RX 6600

[Shane15]

Problem

New AMD Radeon RX 6600 graphics card displays only black screen.

Synopsis

I am looking for anyone that might have some experience replacing an nVidia card with an AMD RX 6600. I’ve spent the better part of a week trying to get this to work and I have tried many more things than I can remember right now. My googlefu has failed me and I’ve started drinking heavily again. Want to start from scratch and figure this out.

Starting Over From Scratch

According to a recent post here in the forum, I should :

1. Switch the video cards
2. sudo mhwd -r pci video-nvidia
3. sudo mhwd -f -i pci video-linux

This obviously won’t work because my screen is black.

A) How can I purge all video drivers AND configs from the system and install what is needed while running the current nvidia card before switching to the new AMD card?

B) What exactly do I need to uninstall/reinstall?

Other Notes :

After plugging in the new card, Manjaro seems to be working because I can Ctl-Alt-Del to bring up the Logout Confirmation Window and use the arrow keys to select the different options to logout, shut down, reboot.

I have a Redo image of my computer before I began this nightmare so that I can restore to begin each attempt without all the things I’ve done to foul the system up.

Current Card : nVidia GeForce GTS 450
Current Drivers Installed : nVidia 390xx
New Card : AMD Radeon RX 6600 128-bit 8GB GDDR6
Manjaro : Latest fully updated.
KDE Plasma : 5.27.6
Kernel : 6.1.38-1
Graphics : X11
CPU : AMD Ryzen 9 5900X 12-Core Processor
Ram : More than most 3rd world countries

[megavolt]

Find the configs:

find /etc/X11/ -type f \( -iname "*mhwd.conf" -or -iname "*xorg.conf"  \)

be sure that these contain instructions for nvidia:

find /etc/X11/ -type f \( -iname "*mhwd.conf" -or -iname "*xorg.conf"  \) -exec sh -c 'echo -e "\n\n>>>{}<<<\n\n" && cat "{}"' \;

and remove them:

find /etc/X11/ -type f \( -iname "*mhwd.conf" -or -iname "*xorg.conf"  \) -exec rm -fv "{}" \;

[Shane15]

I copied the command(s) you gave into the terminal, but it yields nothing, not even an error message.

Using KFind and searching for the files listed in the command resulted in finding one file (/etc/X11/xorg.conf.d/90-mhwd.conf), which is just a link to another file (/etc/X11/mhwd.d/nvidia.conf)

What to do?

[megavolt]

@Shane15

(/etc/X11/xorg.conf.d/90-mhwd.conf)

Remove this file and you are done. Reboot.

[Shane15]

Well, Thank you.
I performed these steps.

1. sudo mhwd -r pci video-nvidia
2. sudo mhwd -f -i pci video-linux
3. Made sure the /etc/X11/mhwd.d/nvidia.conf was deleted. (apparently it was in step 1)
4. Shut down the machine.
5. Installed the new video card.
6. Rebooted. (All is well)

I have no idea what went wrong before, but this worked.
I guess now I need to see if that 12-steps group down the block is still meeting on Wednesdays.