Xorg Configuration for Unregistered Resolution

monitorsresolutionx11xorg

I have a monitor with native resolution of 1600*900_60.00, and the intel on board Gen3 Xeon video chipset (i915).
when i do $> xrandr the 1600x900 resolution is not in the list. I tried to write an xorg configuration for monitor and I placed it on /etc/X11/xorg.conf.d/10-monitor.conf. but i must mess some value in there up; that it ha no effect and doesn't change the resolution.
I am sure the /etc/X11/xorg.conf.d/10-monitor is being read at $> startx because if i put anything wrong like ()*! at that file X won't start and produce an error.
The cvt 1600 900 returns:

1600x900 59.95 Hz (CVT 1.44M9) hsync: 55.99 kHz; pclk: 118.25 MHz 
Modeline "1600x900_60.00"  118.25  1600 1696 1856 2112  900 903 908 934 -hsync +vsync

also the xrandr produce:

xrandr
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 8192 x 8192
VGA1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1024x768       60.0* 
   800x600        60.3     56.2  
   848x480        60.0  
   640x480        59.9  
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
HDMI3 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
DP3 disconnected (normal left inverted right x axis y axis)
  1600x900_60.00�� (0xa5)  118.2MHz
        h: width  1600 start 1696 end 1856 total 2112 skew    0 clock   56.0KHz
        v: height  900 start  903 end  908 total  934

And this is my 10-monitor.config file:

Section "Device" 
Identifier  "Intel i915" 
  Option   "VGA1" #"VGA screen" 
  Driver      "intel"
EndSection 
Section "Monitor" 
  Identifier  "Primary Monitor" 
  Modeline    "1600x900_60.00" 118.25 1600 1696 1856 2112  900 903 908 934 -Hsync +Vsync 
  Option      "PreferredMode" "1600x900" 
EndSection 
Section "Screen" 
     Identifier    "Screen0" 
     Device        "VGA1" 
     DefaultDepth  24 
     SubSection "Display" 
     Depth        24 
     Modes   "1600x900_60.00" 
EndSubSection 
EndSection

Best Answer

You can use the --newmode option of xrandr to add the mode to X; then you can use the --addmode option of xrandr to add the mode to the output you are using. Then you should be able to select the mode using xrandr or a GUI mode selector. 

xrandr --newmode "1600x900_60.00" 118.25 1600 1696 1856 2112  900 903 908 934 -hsync +vsync
xrandr --addmode VGA1 "1600x900_60.00"

To change to the mode using xrandr:

xrandr --output VGA1 --mode "1600x900_60.00"

Unfortunately this solution must be repeated every time you restart (of course you could script it). I found this question looking for more information on how to write the permanent change in xorg.conf.

I plan to try the very simple xorg.conf answer in a similar question

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