Can AMD cards disable dithering like Nvidia can on Linux?

Juicebox

Currently I'm running a gigabyte 3070ti on linux and disabling dithering through Nvidia's X Server settings program. This setup works well for me, i get minimal eyestrain, only after a few hours of use.

I wanted to upgrade my GPU and the best deal i can find is a RX 9070 XT, however i can't find any info online whether or not i can definitively turn dithering off. Does anyone have this GPU or other AMD Gpus on linux? Whats your experience with it?

Alternatives I've considered are a 5070ti, which is 20% more expensive and required me to change my PSU, or alternatively a smaller upgrade of a used 3090, almost half the price of a 5070ti.

jordan

Juicebox

I actually am creating a tool to disable amd dithering for linux. It seems on my rx6600 it defaults to spatial which is way better than temporal but youll be able to turn that off as well. Ill have other options too. Its basically a GUI for the umr tool and also has some xrandr controls.

Juicebox

jordan Alright, thanks for the response! I'll probably go ahead and buy the 9070 then. Any ETA on when the program will be available? Is it x11 only or does it somehow work on wayland as well?

jordan

Juicebox No problem. Ill probably post it on github in the next few weeks but can send it to you privately if youd like to test it. It should work just fine on that im pretty sure. If not I can take a look and try to fix it. I am using x11/cinnamon (cachyos)

The dithering controls rely on gitlab.freedesktop.org/tomstdenis/umr, so you need that installed too. You can technically run the commands manually too but the tool makes it easier to alter these settings

jordan

Juicebox I was looking into it more and I guess xrandr is a x11 thing and not wayland so dithering and truncation will work but not some of the other things that rely on xrandr which doesnt really matter. It should work for what you need it for.

Also when you get the gpu and clone/install UMR, run this cmd and let me know the output
sudo umr --list-blocks | grep dcn

Juicebox

jordan Hi, i just got my 9070xt, heres the output from UMR you requested:
❯ sudo umr --list-blocks | grep dcn

amd164e.dcn315 (3.1.5)

I don't know if its placebo or not but the GPU currently feels way worse than my 3070ti.
I would be grateful if you could send the tool you made so i can try if it'll help.

Sunspark

Here is my contribution from the Steam Deck (RDNA2).

What a hassle this was. Ended up having to build it twice.. first in a distrobox but then it wanted the correct libraries in the OS system which was a hassle and I didn't want the bother of having to copy and edit everything one by one, so I turned off read-only and built it again locally which is fine since I don't need to keep all the dependencies I had to install next time there is an OS update.

(1)(deck@steamdeck app)$ sudo ./umr --list-blocks | grep dcn

vangogh.dcn301 (3.0.1)

Does this help any?

jordan

Sunspark I think that should definitely work. The tool will detect the DCN reported and then make the register changes for that. I can send you the tool in messages if you want to try it? I didnt want to post it to the public until im done with it.

simplex

Juicebox my 3070ti

Could you check in GPU-Z what's memory vendor of your 3070ti ?

Juicebox

UPDATE: It seems to have automatically set itself to 10 bit color, whereas my display uses 8bit +frc to simulate it. I set it to 8 bit and added the xrandr command (xrandr --output DisplayPort-1 --set "max bpc" 8) as an autostarting script. So far it maybe feels better(?), but my eyes are already a bit fried so its hard to tell, i'll update the post tomorrow to reflect my findings.

Juicebox

simplex NVIDIA GeForce RTX 3070 Ti
VRAM type: GDDR6x 256-bit (Micron)

The 9070xt's memory type was hynix in case thats also relevant.

simplex

Juicebox Micron

There are rumors on this forum that Samsung memory is safe, but your experience shows otherwise

Juicebox

simplex I don't see how memory could be relevant but i also don't know nearly enough about this to say that it definitively doesn't. Personally the 3070ti I've been using has been great for me, right now Im trying out switching between the 9070xt and the 3070ti and the 3070ti might just be more comfortable for whatever reason, however I'd only be able to say after a few more days of use.

Are there any good threads/posts which explain why the memory would affect the displayed image?

simplex

Juicebox

My ddr4 more strainy at freqs > 2133 mhz ( base ddr4 ), xmp or manual set not important. z390d + 9600kf platform

Sunspark

Set the environment variable for the compositor to 8 bit as well. By default they are 10 bit. Which is OK if your entire chain is 10 bit.