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  1. #1
    Join Date
    Sep 2017
    Location
    United States
    Posts
    2

    2nd display shows wrong resolution because it's "Unknown"

    I'm using a dual monitor setup on Fedora 26 with one 24" monitor and a TV as my 2nd display. My monitor is connected with HDMI and works fine, the TV is connected with VGA and according to the settings it is unknown and I cannot change the resolution higher than 1024x768 when it is supposed to be 1920x1080 just like my monitor. On Windows 10 it worked on 1920x1080 perfectly. Upon installing Fedora I installed NVIDIA drivers.

    The result of xrandr in the terminal is as follows:
    Code:
    Screen 0: minimum 8 x 8, current 2944 x 1080, maximum 16384 x 16384
    DVI-I-0 connected 1024x768+1920+0 (normal left inverted right x axis y axis) 0mm x 0mm
       1024x768      60.00*+
       800x600       72.19    60.32    56.25  
       640x480       59.94  
       512x384       60.00  
       400x300       72.19  
       320x240       60.05  
    DVI-I-1 disconnected (normal left inverted right x axis y axis)
    HDMI-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 527mm x 296mm
       1920x1080     60.00*+  59.94    50.00    60.05    60.00    50.04  
       1680x1050     59.95  
       1600x1200     60.00  
       1600x900      59.98  
       1440x900      59.89  
       1280x1024     75.02    60.02  
       1280x960      60.00  
       1280x800      59.81  
       1280x720      60.00    59.94    50.00  
       1024x768      75.03    70.07    60.00  
       800x600       75.00    72.19    60.32    56.25  
       720x576       50.00  
       720x480       59.94  
       640x480       75.00    72.81    59.94  
    DP-0 disconnected (normal left inverted right x axis y axis)
    DP-1 disconnected (normal left inverted right x axis y axis)
    DP-2 disconnected (normal left inverted right x axis y axis)
    DP-3 disconnected (normal left inverted right x axis y axis)
    DP-4 disconnected (normal left inverted right x axis y axis)
    DP-5 disconnected (normal left inverted right x axis y axis)
      1920 (0x21e) 173.000MHz -HSync +VSync
            h: width  1920 start 2048 end 2248 total 2576 skew    0 clock  67.16KHz
            v: height 1080 start 1083 end 1088 total 1120           clock  59.96Hz
    the 1920 at the bottom was me trying to use other online guides to fix it myself, which resulted in this error:

    Code:
    X Error of failed request:  BadMatch (invalid parameter attributes)
      Major opcode of failed request:  139 (RANDR)
      Minor opcode of failed request:  18 (RRAddOutputMode)
      Serial number of failed request:  47
      Current serial number in output stream:  48
    This error appears whenever I try to add the mode via xrandr --addmode DVI-I-0 1920.

    On the nvidia-settings application it at least let me move the TV to the right side so I don't have to go left to go right, but again it does not let me change the resolution to be any better. Any help would be much appreciated. Thanks!

  2. #2
    Join Date
    Dec 2013
    Location
    United Kingdom
    Posts
    5,232

    Re: 2nd display shows wrong resolution because it's "Unknown"

    check the TV manual to see what modes are supported over VGA cable, there should be a chart of compatible modes, most won't support 1920x1080. You'd need an HDMI or DVI signal for that, not VGA

  3. #3
    Join Date
    Sep 2017
    Location
    United States
    Posts
    2

    Re: 2nd display shows wrong resolution because it's "Unknown"

    Quote Originally Posted by antikythera
    check the TV manual to see what modes are supported over VGA cable, there should be a chart of compatible modes, most won't support 1920x1080. You'd need an HDMI or DVI signal for that, not VGA
    Yeah, but on Windows 7 and 10 with VGA the TV ran fine on 1920x1080. After doing some research I found this is quite a common problem honestly. And the fact that the default display settings says that it's an Unknown Display shows there is clearly a problem.

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