меня DP-0 отсальные отключил.

В конфиг поправил  пункт HorizSync:
Section "Monitor"
    # HorizSync source: edid, VertRefresh source: edid
...........
    #HorizSync       222.0 - 222.0
    HorizSync       31.0 - 222.0
.............
и клонировал его по путям на всякий случай:
root@pc:/etc/X11# find ./ -name "*.conf"
./xorg.conf
./xorg.conf.d/20-nvidia.conf
С правкой полностью он выглядит так  https://pastebin.com/kgfAaNYe (на всякий случай)

Перезагрузился

--------------------------------------------------------------
xrandr
Screen 0: minimum 8 x 8, current 1440 x 900, maximum 32767 x 32767
DVI-D-0 disconnected (normal left inverted right x axis y axis)
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 connected primary 1440x900+0+0 (normal left inverted right x axis y axis) 600mm x 340mm
   2560x1440    144.00 + 120.00    59.95    59.95
   1920x1080    119.88    60.00    59.94    50.00
   1680x1050     59.95
   1440x900      59.89*
   1280x1024     75.02    60.02
   1280x960      60.00
   1280x800      59.81
   1280x720      60.00    59.94    50.00
   1152x864      75.00
   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-1 disconnected (normal left inverted right x axis y axis)

--------------------------------------------------------------
xrandr --listmonitors
Monitors: 1
 0: +*DP-0 1440/600x900/340+0+0  DP-
--------------------------------------------------------------

xrandr --newmode "1368x768_144.00" 226.50 1368 1480 1624 1880 768 771 781 838 -hsync +vsync

xrandr
Screen 0: minimum 8 x 8, current 1440 x 900, maximum 32767 x 32767
DVI-D-0 disconnected (normal left inverted right x axis y axis)
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 connected primary 1440x900+0+0 (normal left inverted right x axis y axis) 600mm x 340mm
   2560x1440    144.00 + 120.00    59.95    59.95
   1920x1080    119.88    60.00    59.94    50.00
   1680x1050     59.95
   1440x900      59.89*
   1280x1024     75.02    60.02
   1280x960      60.00
   1280x800      59.81
   1280x720      60.00    59.94    50.00
   1152x864      75.00
   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-1 disconnected (normal left inverted right x axis y axis)
  1368x768_144.00 (0x200) 226.500MHz -HSync +VSync
        h: width  1368 start 1480 end 1624 total 1880 skew    0 clock 120.48KHz
        v: height  768 start  771 end  781 total  838           clock 143.77H
--------------------------------------------------------------

xrandr --addmode DP-0 "1368x768_144.00"
X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  140 (RANDR)
  Minor opcode of failed request:  18 (RRAddOutputMode)
  Serial number of failed request:  35
  Current serial number in output stream:  36
--------------------------------------------------------------
Эту команду нет смысла пробовать так как нету в DP-0 этого расширения в изза ошибки выше X Error of failed request:
xrandr --output DP-0 --mode 1368x768_144.00
xrandr: cannot find mode 1368x768_144.00
--------------------------------------------------------------
xrandr
Screen 0: minimum 8 x 8, current 1440 x 900, maximum 32767 x 32767
DVI-D-0 disconnected (normal left inverted right x axis y axis)
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 connected primary 1440x900+0+0 (normal left inverted right x axis y axis) 600mm x 340mm
   2560x1440    144.00 + 120.00    59.95    59.95
   1920x1080    119.88    60.00    59.94    50.00
   1680x1050     59.95
   1440x900      59.89*
   1280x1024     75.02    60.02
   1280x960      60.00
   1280x800      59.81
   1280x720      60.00    59.94    50.00
   1152x864      75.00
   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-1 disconnected (normal left inverted right x axis y axis)
  1368x768_144.00 (0x200) 226.500MHz -HSync +VSync
        h: width  1368 start 1480 end 1624 total 1880 skew    0 clock 120.48KHz
        v: height  768 start  771 end  781 total  838           clock 143.77Hz