Comment avoir sur une seule machine la gestion du double écran alors que l'on n'a pas de double sortie sur sa carte vidéo ?

Avec linux c'est possible

installez votre carte vidéo dans un emplacement PCI libre

au démarrage en console tapez : lspci | grep VGA

vous trouverez les caractéristique de vos cartes vidéo et notamment de la  nouvelle installée

ex pour moi  :

00:02.0 VGA compatible controller: Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device (rev 03)
01:00.0 VGA compatible controller: Trident Microsystems 3DImage 9750 (rev f3)

j'ai donc le fichier /etc/X11/xconf.org suivant

 # /etc/X11/xorg.conf (xorg X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the xorg.conf(5) manual page.
# (Type "man xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
#   sudo dpkg-reconfigure -phigh xserver-xorg

Section "Files"
  FontPath "/usr/share/fonts/X11/misc"
  FontPath "/usr/share/fonts/X11/cyrillic"
  FontPath "/usr/share/fonts/X11/100dpi/:unscaled"
  FontPath "/usr/share/fonts/X11/75dpi/:unscaled"
  FontPath "/usr/share/fonts/X11/Type1"
  FontPath "/usr/share/fonts/X11/100dpi"
  FontPath "/usr/share/fonts/X11/75dpi"
  # path to defoma fonts
  FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
EndSection

Section "Module"
  Load "i2c"
  Load "bitmap"
  Load "ddc"
  Load "extmod"
  Load "freetype"
  Load "int10"
  Load "vbe"
  load "glx"
  load "GLcore"
  load "v4l"
EndSection

Section "InputDevice"
  Identifier "Generic Keyboard"
  Driver "kbd"
  option "CoreKeyboard"
  option "XkbRules" "xorg"
  option "XkbModel" "pc105"
  option "XkbLayout" "fr"
  option "XkbVariant" "oss"
EndSection

Section "InputDevice"
  Identifier "Configured Mouse"
  Driver "mouse"
  option "CorePointer"
  option "Device" "/dev/input/mice"
  option "Protocol" "ImPS/2"
  option "ZAxisMapping" "4 5"
  option "Emulate3Buttons" "true"
EndSection

Section "InputDevice"
  Driver "wacom"
  Identifier "stylus"
  option "Device" "/dev/input/wacom"
  option "Type" "stylus"
  option "ForceDevice" "ISDV4"# Tablet PC ONLY
EndSection

Section "InputDevice"
  Driver "wacom"
  Identifier "eraser"
  option "Device" "/dev/input/wacom"
  option "Type" "eraser"
  option "ForceDevice" "ISDV4"# Tablet PC ONLY
EndSection

Section "InputDevice"
  Driver "wacom"
  Identifier "cursor"
  option "Device" "/dev/input/wacom"
  option "Type" "cursor"
  option "ForceDevice" "ISDV4"# Tablet PC ONLY
EndSection

Section "Device"
  identifier "Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device"
  boardname "i810"
  busid "PCI:0:2:0"
  driver "i810"
  screen 0
EndSection

Section "Device"
  identifier "Trident Microsystems 3DImage 9750"
  boardname "Trident 3DImage975 (generic)"
  busid "PCI:1:0:0"
  driver "trident"
  screen 0
  vendorname "Trident"
EndSection

Section "Monitor"
  identifier "Generic Monitor"
  vendorname "Acer"
  modelname "Aspire 77s"
  HorizSync 30.0-72.0
  VertRefresh 50.0-120.0
  modeline  "640x480@60" 25.2 640 656 752 800 480 490 492 525 -vsync -hsync
  modeline  "640x480@72" 31.5 640 664 704 832 480 489 491 520 -vsync -hsync
  modeline  "640x480@75" 31.5 640 656 720 840 480 481 484 500 -vsync -hsync
  modeline  "640x480@85" 36.0 640 696 752 832 480 481 484 509 -vsync -hsync
  modeline  "800x600@56" 36.0 800 824 896 1024 600 601 603 625 +hsync +vsync
  modeline  "800x600@72" 50.0 800 856 976 1040 600 637 643 666 +hsync +vsync
  modeline  "800x600@75" 49.5 800 816 896 1056 600 601 604 625 +hsync +vsync
  modeline  "800x600@85" 56.3 800 832 896 1048 600 601 604 631 +hsync +vsync
  modeline  "800x600@60" 40.0 800 840 968 1056 600 601 605 628 +hsync +vsync
  modeline  "832x624@75" 57.284 832 864 928 1152 624 625 628 667 -vsync -hsync
  modeline  "1024x768@85" 94.5 1024 1072 1168 1376 768 769 772 808 +hsync +vsync
  modeline  "1024x768@75" 78.8 1024 1040 1136 1312 768 769 772 800 +hsync +vsync
  modeline  "1024x768@70" 75.0 1024 1048 1184 1328 768 771 777 806 -vsync -hsync
  modeline  "1024x768@60" 65.0 1024 1048 1184 1344 768 771 777 806 -vsync -hsync
  modeline  "1024x768@43" 44.9 1024 1032 1208 1264 768 768 776 817 +hsync interlace +vsync
  modeline  "1152x864@75" 108.0 1152 1216 1344 1600 864 865 868 900 +hsync +vsync
  modeline  "1280x960@60" 102.1 1280 1360 1496 1712 960 961 964 994 -hsync +vsync
  modeline  "1280x1024@60" 108.0 1280 1328 1440 1688 1024 1025 1028 1066 +hsync +vsync
  modeline  "1400x1050@60" 122.61 1400 1488 1640 1880 1050 1051 1054 1087 -hsync +vsync
  gamma 1.0
EndSection

Section "Monitor"
  identifier "Monitor2"
  vendorname "Generic"
  modelname "Flat Panel 1024x768"
  HorizSync 31.5-55
  VertRefresh 40-70
  modeline  "640x480@60" 25.2 640 656 752 800 480 490 492 525 -vsync -hsync
  modeline  "800x600@56" 36.0 800 824 896 1024 600 601 603 625 +hsync +vsync
  modeline  "800x600@60" 40.0 800 840 968 1056 600 601 605 628 +hsync +vsync
  modeline  "1024x768@60" 65.0 1024 1048 1184 1344 768 771 777 806 -vsync -hsync
  gamma 1.0
EndSection

Section "Screen"
  Identifier "Default Screen"
  Device "Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device"
  Monitor "Generic Monitor"
  DefaultDepth 24
  SubSection "Display"
    depth 24
    modes "1280x1024@60" "1400x1050@60" "1280x960@60" "1152x864@75" "1024x768@43" "1024x768@60" "1024x768@70" "1024x768@75" "1024x768@85" "832x624@75" "800x600@60" "800x600@85" "800x600@75" "800x600@72" "800x600@56" "640x480@85" "640x480@75" "640x480@72" "640x480@60"
  EndSubSection
EndSection

Section "Screen"
  Identifier "Screen2"
  Device "Trident Microsystems 3DImage 9750"
  Monitor "Monitor2"
  DefaultDepth 24
  SubSection "Display"
    depth 24
    modes "1024x768@60" "800x600@60" "800x600@56" "640x480@60"
  EndSubSection
EndSection

Section "ServerLayout"
  Identifier "Default Layout"
  screen 0 "Default Screen" 0 0
  screen 1 "Screen2" rightof "Default Screen"
  InputDevice "Generic Keyboard"
  InputDevice "Configured Mouse"
  InputDevice "stylus" "SendCoreEvents"
  InputDevice "cursor" "SendCoreEvents"
  InputDevice "eraser" "SendCoreEvents"
  option "Xinerama" "on"
#"-" "Using" "/etc/X11/Xorg.conf"
  option "Clone" "off"
EndSection

Section "DRI"
  Mode 0666
EndSection
Section "ServerFlags"
  option "Xinerama" "true"
EndSection