:# xrandr
Screen 0: minimum 320 x 200, current 1680 x 1050, maximum 1680 x 1680
DFP1 connected 1680x1050+0+0 (normal left inverted right x axis y axis) 474mm x 296mm
1680x1050 59.9*+
1400x1050 60.0 +
1152x648 60.0 +
1280x1024 75.0 60.0
1440x900 59.9
1280x960 75.0 60.0
1280x800 75.0 60.0
1152x864 75.0 60.0
1280x768 74.9 59.9
1280x720 60.0
1024x768 75.0 60.0
800x600 75.0 60.3 56.2
720x480 60.0
640x480 75.0 60.0
DFP2 disconnected (normal left inverted right x axis y axis)
CRT1 connected (normal left inverted right x axis y axis)
1600x1200 60.0 +
1400x1050 60.0
1280x1024 60.0 47.0 43.0
1440x900 59.9
1280x960 60.0
1280x800 60.0
1152x864 60.0 47.0 43.0
1280x768 59.9 56.0
1280x720 60.0 50.0
1024x768 60.0 43.5
800x600 60.3 56.2 47.0
720x576 50.0
720x480 60.0
640x480 60.0
CRT2 disconnected (normal left inverted right x axis y axis)
TV disconnected (normal left inverted right x axis y axis)
CV disconnected (normal left inverted right x axis y axis)
800x600x (0xbe) 16.0MHz
h: width 800 start 840 end 920 total 1040 skew 0 clock 15.4KHz
v: height 600 start 602 end 605 total 627 clock 24.5Hz
:# xrandr --newmode "800x600x" 16,48 800 840 920 1040 600 602 605 627 interlace -hsync -vsync
:# xrandr --addmode CRT1 800x600x
X Error of failed request: BadMatch (invalid parameter attributes)
Major opcode of failed request: 162 (RANDR)
Minor opcode of failed request: 18 ()
Serial number of failed request: 19
Current serial number in output stream: 20