(SOLVED) Occasional screen flicker and black square around windows

[roblm]

You can test using a mode with a lower refresh rate, which will then be below the pixel clock limit of 165 MHz. This mode is using 54 Hz and was generated by umc (universal modeline calculator).

Change the Modeline in the xorg.conf file to this:

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Modeline "2560x1080_53.92"  162.50  2560 2608 2640 2720  1080 1083 1087 1108  +HSync -VSync

Change the MetaModes line to this:

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Option "MetaModes" "DP-0: 2560x1080_53.92 +1920+0, DP-1: nvidia-auto-select +0+0"

Also, test a mode with a 50 Hz refresh rate:

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Modeline "2560x1080_49.94"  150.25  2560 2608 2640 2720  1080 1083 1087 1106  +HSync -VSync
Option "MetaModes" "DP-0: 2560x1080_49.94 +1920+0, DP-1: nvidia-auto-select +0+0"

[redpinkoZ1917]

You can test using a mode with a lower refresh rate, which will then be below the pixel clock limit of 165 MHz. This mode is using 54 Hz and was generated by umc (universal modeline calculator).

Change the Modeline in the xorg.conf file to this:

Code: Select all

Modeline "2560x1080_53.92"  162.50  2560 2608 2640 2720  1080 1083 1087 1108  +HSync -VSync

Change the MetaModes line to this:

Code: Select all

Option "MetaModes" "DP-0: 2560x1080_53.92 +1920+0, DP-1: nvidia-auto-select +0+0"

Also, test a mode with a 50 Hz refresh rate:

Code: Select all

Modeline "2560x1080_49.94"  150.25  2560 2608 2640 2720  1080 1083 1087 1106  +HSync -VSync
Option "MetaModes" "DP-0: 2560x1080_49.94 +1920+0, DP-1: nvidia-auto-select +0+0"

Code: Select all

[ 20698.207] (WW) NVIDIA(GPU-0):     Mode is rejected: VertRefresh (53.9 Hz) out of range
[ 20698.207] (WW) NVIDIA(GPU-0):     (56.000-75.000 Hz).

How do I circumvent this? I haven't been able to find a refresh rate that falls within both parameters.

[roblm]

Oops! I forgot about checking that supported 56.00-75.00 Hz range. You would have to change the line in the xorg.conf file to VertRefresh 54.0 - 75.0, but that is probably not a good idea.

[redpinkoZ1917]

Oops! I forgot about checking that supported 56.00-75.00 Hz range. You would have to change the line in the xorg.conf file to VertRefresh 54.0 - 75.0, but that is probably not a good idea.

No problem. I'll just wait for the new hardware. Thanks again, and happy new year! As it turns out, my switch does support 4k but only a 30hz refresh rate for it, so hopefully this new switch will solve the problem.

[redpinkoZ1917]

So the new switch solved my problem. I switched from this to this.

I am thinking it has to do with the EDID emulator, the 60hz refresh rate compatibility, or both in the new KVM switch. Hopefully this thread might help someone in the future.

Cheers!

[flabo]

I didn't try all of the above, but I tried a lot of it... In the end this worked for me:

Menu -> System Settings -> General -> Enable VBlank (Requires Cinnamon Restart) -> Restart

Works

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System:
  Host: grammy Kernel: 5.3.0-46-generic x86_64 bits: 64 
  Desktop: Cinnamon 4.0.10 Distro: Linux Mint 19.1 Tessa 
Machine:
  Type: Laptop System: LG product: 17ZD990-VX50K v: 0.1 
  Mobo: LG model: 17Z990 v: FAB1 serial: <root required> UEFI: Phoenix 
Graphics:
  Device-1: Intel driver: i915 v: kernel 
  Display: x11 server: X.Org 1.19.6 driver: modesetting unloaded: fbdev,vesa 
  resolution: 1920x1200~60Hz, 1920x1080~60Hz 
  OpenGL: renderer: Mesa DRI Intel UHD Graphics (Whiskey Lake 3x8 GT2) 
  v: 4.5 Mesa 19.2.8 

kthxbi