Swapping GPUs
Be sure to go to /etc/X11 and clear out the xorg.conf and xorg.conf.d folder if you are getting a blank screen on boot.
Monitor Offsets in GNOME
GNOME stores its own display settings in ~/config/monitors.xml
In my case I want Monitor 1 (on DP-2) to be offset 70 px to the right and sitting on Monitor 2 (on DP-3) so I need to manually edit the monitors.xml file to get that to be loaded by GNOME on future saves.
To position in Xorg, you need to use xrandr:
# get current setup
xrandr --current
xrandr --output DP-2 --pos 70x0
xrandr --output DP-3 --pos 0x1440
Hardware Acceleration
https://wiki.archlinux.org/title/Hardware_video_acceleration libva-utils
AMD
xf86-video-amdgpu amdgpu-pro-libgl vulkan-amdgpu-pro
Nvidia
nvidia-dkms - Use DKMS drivers to not have to deal nvidia-utils opencl-nvidia
Video
libva-nvidia-driver (github) - thise supports NVDEC via VAAPI. There is a git version nvidia-vaapi-driver-git as well.
Firefox
https://wiki.archlinux.org/title/Hardware_video_acceleration#Verifying_VA-API
about:support - Compositing should be WebRender, HARDWARE_VIDEO_DECODING https://wiki.archlinux.org/title/Firefox#Hardware_video_acceleration
https://www.reddit.com/r/firefox/comments/o8brga/unable_to_utilize_hardware_acceleration_in/ https://www.reddit.com/r/archlinux/comments/xbhxs2/trouble_setting_up_firefox_hardware_video_decoding/