No 4K/144hz option with AMD GPU

Hey folks, new Bazzite user. I’m trying to switch to Linux from Windows, I’ve jumped between Bazzite GNOME/Nobara/Bazzite KDE/CachyOS and back to Bazzite KDE, deciding it seemed to strike the right balance for me. Understanding that AMD cards (generally) work better on Linux systems, I picked up an RX 7900 XTX during Prime Day to replace my 3080, which just hasn’t been giving me the frames I wanted on newer titles for awhile. (Ever since I switched to 4K in 2022, basically.) With my RTX 3080 previously, I was able to use my monitor (LG C4 42”) in 144hz mode via HDMI 2.1. This is true in Windows as well as Bazzite and other Linux distros. Now with the 7900XTX, I’m only seeing as high as 120hz being an option, despite the TV settings being at the full 144hz. My cables haven’t changed, so I know that’s not the issue. (Admittedly I didn’t check Windows to confirm the 7900XTX is pushing 4K/144hz there.) Any suggestions for getting this working right?
9 Replies
Lixo
Lixo5w ago
The HDMI forum blocks the open-source AMD driver from implementing support for HDMI 2.1, it's stuck on 2.0 that's why you can only see 120 Hz, no way to fix it but the workaround is using DisplayPort
Physek
PhysekOP5w ago
Ah darn. So it works on NVIDIA but borked on AMD? Why would they block that! Seems silly… Unfortunately there’s no way for my LG C4 to use DisplayPort.
Lixo
Lixo5w ago
Not silly, evil https://www.phoronix.com/news/HDMI-2.1-OSS-Rejected Does it have USB C with DP? That could also work
Physek
PhysekOP5w ago
So what I’m reading is that the HDMI forum refuses to explain the requirements, and then is shooting down the proposal because it fails to meet the standards set by those requirements, which nobody knows what they are…? That’s absolutely ridiculous. LG C4 is a TV, unfortunately. 4xHDMI 2.1 are the only inputs, I think. I’m not too concerned. The difference between 120hz and 144hz isn’t crazy! Definitely a bit sad though. @Lixo Perhaps a silly question but is it possible to use closed-source drivers that do have the HDMI 2.1 capability?
Kyle Gospo
Kyle Gospo5w ago
the AMD closed source drivers are garbage not worth it you'd be trading framerate so your display can work at a higher refres hrate
termdisc
termdisc5w ago
ignoring the issue in the OP's question, this user seems to go as high as 4K/120 with the same GPU
Lixo
Lixo5w ago
I don't think it's that, some time ago the HDMI specification was public, there were still fees to implement it but you could do it, then they made it only accessible to HDMI adopters probably to make this "using without paying fees" more difficult, then the forum ruled that AMD, an adopter, by implementing it in the open source driver, would be infringing this and that's where we're at
Physek
PhysekOP5w ago
I’m getting 4K/120, though from what I’m reading the expectation at that resolution/refresh rate is that the color space should be severely (perhaps crippling) limited. I’m going to run some tests once I’m home from work.
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