How can I confirm my new graphics card is installed correctly?

[Riquez]

OK, makes sense to just use xorg.

reviewing some of the info…

xrandr --listproviders                                           ✔ 
Providers: number : 2
Provider 0: id: 0x55 cap: 0xf, Source Output, Sink Output, Source Offload, Sink Offload crtcs: 4 outputs: 3 associated providers: 1 name:AMD Radeon Graphics @ pci:0000:08:00.0
Provider 1: id: 0x78 cap: 0xf, Source Output, Sink Output, Source Offload, Sink Offload crtcs: 2 outputs: 2 associated providers: 1 name:AMD Radeon RX 6400 @ pci:0000:03:00.0

lspci | grep VGA                                                 ✔ 
03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Navi 24 [Radeon RX 6400/6500 XT/6500M] (rev c7)
08:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Renoir [Radeon RX Vega 6 (Ryzen 4000/5000 Mobile Series)] (rev da)

For Discrete card as primary GPU I need to create a conf file:
I am aiming to get the dGPU used for everything, so I can access grub & hopefully see some higher frame rates in games with iGPU out of the picture.

Below is my best guess at what to change, but I feel lost knowing what the valid values are supposed to be. Does this look right?

/etc/X11/xorg.conf.d/10-gpu.conf
# I only have a 00-keyboard.conf in this location, so ill create 10-gpu.conf

Section "ServerLayout"
    Identifier "layout" 
    Screen 0 "rx6400"
    Inactive "igpu"
EndSection

Section "Device"
    Identifier  "igpu" # user defined
    Driver      "amdgpu" # I guess??
    BusID       "PCI:8:0:0" 
EndSection

Section "Screen"
    Identifier "radeon"
    Device "radeon" # guess
EndSection

Section "Device"
    Identifier  "rx6400"
    Driver      "amdgpu"
    BusID       "PCI:3:0:0"
EndSection

Section "Screen"
    Identifier "radeon" #guessing
    Device "radeon"
EndSection

do you have KMS properly configured?
(amdgpu in modules and kms in hooks of mkinitcpio.conf)

HOOKS=(base udev autodetect kms modconf block keyboard keymap consolefont plymo>
MODULES=() 

I added amdgpu to modules '& ran sudo mkinitcpio -P. Rebooted but no video output for grub still.

HOWEVER - I am now seeing 60fps in Elite & up to 400fps in some platformers. (with or without DRI_PRIME=1 %command% ) could it be that xorg has made that improve? ill have to check.
ANSWER: yes amazingly. after several reboots. xorg gets 60fps, wayland 30
(On my laptop Elite runs about the same on xorg/wayland)

[Riquez]

I was about to give up & try another distro, but I’ll just post what transpired for posterity.

xorg kept crashing the compositor (desktop img disappeared, shell menus freeze up, shadows are over exaggerated, etc) so I re-installed manajro.
This time I just tried DRI_PRIME=1 %command% in Steam right from the start & used the motherboard HDMI. This seems to be working.

The results are a little underwhelming in most games but significant in others. I tried DRI_PRIME=0 to compare.
Linux games in steam ; Firewatch on ultra get 80fps Prime=1, 25fps without.
Proton games : Elite Dangerous, A Plague Tale are 60fps with either card & Ultra dips slightly 50-55 which is much better than before. - although I feel this is a software/driver issue resolved by the re-install because both were on 30fps previously.
Some platform games show 400fps.
Its possible the 60fs cap in some games could be related to the TV screen being 60hz. Im not sure.

The rx6400 is supposed to be significantly better than the iGPU, between 300-900% better going by the online comparisons.
So I am left feeling I got a few fps & a noisy fan for the cost/effort. But ill see how it goes over time.
It was never going to be an amazing game machine, I just need it to get by with modest settings & last gen games.

I did learn some stuff, so thats ok. It was a bit of a nightmare, so really my main lesson was “should have bought a console” LOL

EDIT: I was too late to add before topic was closed.
I am new to graphics card & PC gaming, so there’s a lot I didn’t comprehend.
My TV is 60hz, when vSync is ON in a game this limits the fps to 60 to match the TV.
When I disable that I can now see around 150fps depending on the game.
Also, resolution & quality setting in the game have an effect.

SO I can run A Plague Tale at ultra, 1080p & it will just about maintain 60fps, but the fans are really going & temps rising. If I set 720p, Ultra, I can get a stable 60fps without fans blasting.
If I turn vsync off frames increase, but so do fans in graphically heavy games.
So I think everything is working but being a total beginner I couldn’t understand what was going on.

[cscs]

If its ‘working’ now … you just dont get quite the performance you would expect … then I suppose the next steps would be configuration.

One stop would be power management - many systems will have power-profiles or tlp or something similar that will automatically restrict performance under battery.

Or general gfx configuration as seen at the arch wiki:

https://wiki.archlinux.org/title/AMDGPU#Xorg_configuration

(if you want assistance with running down any possible issues or gaining other advice you may want to start a new thread with that purpose)