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Running the GPU performance setting at "automatic", vram (mclk) clocks works correctly. (max clock at : 2516 Mhz)
Running the performance setting at manual "highest clocks", vram clock is stuck at below max speed, at 2248 Mhz
..Why not just run it in "automatic" then? - Because my 240Hz monitor blanks screen a couple of seconds quite often, when vram clock changes downwards.
This looks like a bug in amdgpu? - I reports the max clock, but refuses to select it in the static "highest clock" mode, but works in automatic.
# cat /sys/class/drm/card1/device/power_dpm_force_performance_level
high
# cat /sys/class/drm/card1/device/pp_dpm_mclk
0: 96Mhz
1: 456Mhz
2: 772Mhz
3: 875Mhz
4: 1124Mhz *
5: 1258Mhz ..Also, the kernel interface reports the vram clocks /2. Dunno why.
Desktop rig, AMD RX 9070 XT GPU. Fully up-to-date all packages, using amdgpu. Same story on X11/Wayland, KDE/Gnome.
Last edited by asaaby (2026-01-13 20:06:51)
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Could be a bandwidth issue?
You may need a better display port cable, do you have one? Did you get one with the monitor and just used the old one? The reason I think this is in one of your other posts it states:
Setup:
Hardware description:
CPU: AMD 7950X
GPU: AMD RX 9070XT
System RAM: 32GB
Display: Samsung OLED G95SC 49" 5120x1440 @240hz (latest 4048 software/firmware)
Display connection: DisplayPort 1.4System description:
Arch Linux
Linux kernel 6.18.1
linux-firmware-amdgpu 20251125-2
Mesa 25.3.1
KDE Plasma 6.5.4, Wayland session
5120x1440 @240hz no-vrr no-hdr
'Display connection: DisplayPort 1.4' - > the 9070xt has a display port version 2.1/2.1a and you are almost at 4k with the ultrawide
For bandwidth considerations check the following site:
https://linustechtips.com/topic/729232- … ction=calc
Edit: bad post, monitor uses 1.4 -> fail
Last edited by IFailALot (2026-01-17 12:22:27)
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I don't think it's directly a bandwidth issue, as the GPU will happily clock vram (mclk) to 2516 Mhz in "auto" mode.
But it looks as if it is related to some timing mechanics of the blanking period of the monitor, on high bandwidth / latency sensitive setups, when reclocking vram, I just found this issue reported by others here:
https://gitlab.freedesktop.org/drm/amd/-/issues/4753
The DP cable is 2.1 capable, but the monitor, a 49" Samsung G9 Odyssey OLED, is unfortunately only capable of DP 1.4. (or HDMI 2.1 - but that won't fly on AMD/Linux).
Last edited by asaaby (2026-01-20 14:15:25)
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For future reference, I now have a patch/workaround, as of the work done in this thread:
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