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I created a custom 65hz 1600x900 refresh rate with CVT 1.2 and set it with XRandR. The screen flickers when setting it but glxgears it still shows the vsynced frame rate as 60fps instead of 65.

XRandR shows the monitor is running at 65hz. Monitor is laptop internal LVDS screen and pixel clock limit is not exceeded.

I also tried creating a EDID with the custom refresh rate using drm_kms_helper.edid_firmware and it made the boot screens run at the refresh rate but when the greeter is started the screen flickers and is set back to 60hz (I tested with 10hz so I can see the lag clearly and later tried 65hz)

I also tried TestUFO motion tests using Chromium and they also showed 60fps.

Kubuntu 17.04 and GPU is Radeon HD 7640G with padoka / xorg edgers drivers.

65hz Modeline

Modeline "1600x900_65.00_rb"  106.74  1600 1648 1680 1760  900 923 928 934 +hsync -vsync

Commands used

xrandr --newmode "1600x900_65.00_rb"  106.74  1600 1648 1680 1760  900 923 928 934 +hsync -vsync
xrandr --addmode LVDS 1600x900_65.00_rb
xrandr --output LVDS --mode 1600x900_65.00_rb --verbose

glxgears still shows 60fps

  • Can you update your question with the text output from CVT and the text input lines you passed to xrandr? – WinEunuuchs2Unix Jul 24 '17 at 16:24
  • i have updated the question – Suici Doga Jul 25 '17 at 3:58
  • Whilst reading up on your problem I found this comprehensive article: mythtv.org/wiki/Modeline_Database – WinEunuuchs2Unix Jul 25 '17 at 4:58
  • what is the problem and my monitor is an internal laptop screen not a tv – Suici Doga Jul 25 '17 at 7:46
  • How much Hz is your display supposed to be able to handle? usually the auto recognization is working pretty good and uses the maximum amount anyway. So the only reason I would see to set Hz manually is to reduce the rate and not try to go over it. The flickering suggests me that I am right and your screen is actually on the limit with 60 already. Rather tell us the model of your laptop. – Ziazis Jul 27 '17 at 13:15

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