Depois que eu instalei drivers Nvidia, eu consegui configurar o monitor externo como eu queria através do arquivo de configuração /etc/X11/xorg.conf :
Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
Option "Xinerama" "0"
EndSection
Section "Files"
EndSection
Section "InputDevice"
# generated from default
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/psaux"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection
Section "InputDevice"
# generated from default
Identifier "Keyboard0"
Driver "kbd"
EndSection
Section "Monitor"
Identifier "Monitor0"
VendorName "Unknown"
ModelName "SAMSUNG"
HorizSync 26.0 - 81.0
VertRefresh 24.0 - 75.0
Option "DPMS"
Option "DPI" "96 x 96"
EndSection
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce GTX 960M"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
Option "UseEdidDpi" "False"
Option "Stereo" "0"
Option "nvidiaXineramaInfoOrder" "DFP-0"
Option "metamodes" "1680x1050 +0+0"
Option "SLI" "Off"
Option "MultiGPU" "Off"
Option "BaseMosaic" "off"
SubSection "Display"
Depth 24
EndSubSection
EndSection
Mas como configuro o modo de tela dupla? nvidia-settings detecta apenas um monitor, assim como xrandr -q :
Screen 0: minimum 8 x 8, current 1680 x 1050, maximum 16384 x 16384
HDMI-0 connected primary 1680x1050+0+0 (normal left inverted right x axis y axis) 160mm x 90mm
1920x1080 60.00 + 59.94 50.00 29.97 25.00 23.98 60.05 60.00 50.04
1680x1050 59.95*
1600x1200 60.00
1440x900 74.98 59.89
1360x768 60.02
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
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)
Além disso, se for possível, eu gostaria de ter comutação automática entre Intel e Nvidia GPU, já que eu tenho ambos (dual GPU). Isso funciona no Windows 10 fora da caixa.