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Two AMD power management related scenarios causes a 5120x1440 @240hz monitor to regularly <blank> for a few seconds:
1: Low performance desktop scenario:
- amdgpu power management in standard "automatic" mode
- will cause VRAM clocks to scale with performance needed, between 192 Mhz and 2516 Mhz
Problem: Often when VRAM clock changes downwards, it causes the screen to <blank> for a few seconds.
Workaround(80%): Change amdgpu power management from "automatic" to "fixed high", which (mostly) causes the GPU to fix VRAM clock to 2248Mhz, which (mostly) makes the screen <blanks> to go away. - I suspect it only partly fixed the problem, because I cannot force VRAM clock to highest speed.
2: High performance scenario:
- amdgpu power management in "fixed high" (or "manual") with fixed VRAM clock
- will cause VRAM clock to be fixed at 2248 Mhz (Notably NOT at max frequency 2516 Mhz)
Problem: When running high performance 3D games, screen <blanks> when enough of the screen changes
Workaround(100%): Change amdgpu power management from "fixed" back to "automatic", which causes the VRAM clock to stay at 2516Mhz, which makes the screen <blanks> to completely go away.
Side note: Problem is most annoying when running 240Hz, but is also visible in 120hz mode: Instead of the screen blanking, a white line, ~2cm wide, will appear on screen for a split second, in the same scenarios as when 240hz would blank.
...So I can make the screen mostly stable in both normal desktop mode and fully stable in games, by selecting the "right" power management profile.
I think I have found a couple of bugs in the kernel driver (or firmware):
1: Normal "automatic" mode, makes this big screen "unstable", unusable in normal desktop scenarios, because of the constant blanking, when power management changes VRAM clock downwards.
2: Fixed VRAM clock mode, cannot select the highest clock (2516Mhz), which I suspect is the reason for screen blanks happening in high performance gaming situations in this mode.
See details described here for the kernel pm interface wrong behavior:
https://gitlab.freedesktop.org/drm/amd/ … oxNDUwNDl9
Any ideas, what I can do/try to make this work properly?
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 1.4
System 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
Last edited by asaaby (2025-12-21 09:06:56)
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Use automatic power management for normal desktop use to avoid VRAM downclock blanks, and switch to fixed or forced max VRAM clock (around 2516MHz) for gaming to prevent blanks. Keep kernel, Mesa, and amdgpu firmware updated. Tools like CoreCtrl or rocm-smi can help set clocks and switch profiles dynamically. Reducing refresh rate to 120Hz can also reduce desktop artifacts.
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Yes, but that is the strategy which does not work.
1: automatic in normal desktop mode <will> downclock, which causes the screen blanks.
2: fixed/forced <will not> go to max frequency (2516Mhz), which will cause cause screen blanks in performance gaming scenarios.
I have tried manipulating the power/performance modes using: lacp, corectl, raw kernel interfaces in /sys. Same result for all.
Example: (for some reason the /sys interface shows clock speeds /2?)
[root@lint ~]# cat /sys/class/drm/card1/device/power_dpm_force_performance_level
manual
[root@lint ~]# echo "5" > /sys/class/drm/card1/device/pp_dpm_mclk
[root@lint ~]# cat /sys/class/drm/card1/device/pp_dpm_mclk
0: 96Mhz
1: 456Mhz
2: 772Mhz
3: 875Mhz
4: 1124Mhz *
5: 1258MhzAll packages are up to date.
..Yeah, reducing to 120hz will make the problem less prominent, but is just not as glorious for FPS gaming as 240hz.
Last edited by asaaby (2025-12-21 11:46:39)
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