olá...
Olha, placa sis 671/771 com aceleção 3d não funciona bem. Se vc conseguir instalá-la vc ao mesmo tempo não conseguirá assistir videos no youtube, em fullscreen de qualidade, por exemplo.
Minha dica é que apenas vá em /etc/X11 como root e veja se vocẽ tem um arquivo chamado xorg.conf
Se sim, apague seu conteúdo depois de salvá-lo em local seguro e cole esse código:
# /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 /etc/X11/xorg.conf manual page.
# (Type "man /etc/X11/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 "ServerFlags"
Option "AllowMouseOpenFail" "true"
EndSection
Section "Files"
FontPath "/usr/share/fonts/X11/misc"
FontPath "/usr/X11R6/lib/X11/fonts/misc"
FontPath "/usr/share/fonts/X11/cyrillic"
FontPath "/usr/X11R6/lib/X11/fonts/cyrillic"
FontPath "/usr/share/fonts/X11/100dpi/:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/100dpi/:unscaled"
FontPath "/usr/share/fonts/X11/75dpi/:unscaled"
FontPath "/usr/X11R6/lib/X11/fonts/75dpi/:unscaled"
FontPath "/usr/share/fonts/X11/Type1"
FontPath "/usr/X11R6/lib/X11/fonts/Type1"
FontPath "/usr/share/fonts/X11/100dpi"
FontPath "/usr/X11R6/lib/X11/fonts/100dpi"
FontPath "/usr/share/fonts/X11/75dpi"
FontPath "/usr/X11R6/lib/X11/fonts/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 "dri"
Load "extmod"
Load "freetype"
Load "glx"
Load "int10"
Load "vbe"
EndSection
Section "InputDevice"
Identifier "Generic Keyboard"
Driver "kbd"
Option "CoreKeyboard"
Option "XkbRules" "xorg"
Option "XkbModel" "abnt2"
Option "XkbLayout" "br"
Option "XkbVariant" "abnt2"
EndSection
Section "InputDevice"
Identifier "Serial Mouse"
Driver "mouse"
Option "Protocol" "Microsoft"
Option "Device" "/dev/ttyS0"
Option "Emulate3Buttons" "true"
Option "Emulate3Timeout" "70"
Option "SendCoreEvents" "true"
EndSection
Section "InputDevice"
Identifier "USB Mouse"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/input/mice"
Option "SendCoreEvents" "true"
Option "ZAxisMapping" "4 5"
Option "Buttons" "5"
EndSection
Section "Device"
Identifier "Silicon Integrated Systems [SiS] 5597 [SiS5582]"
Driver "vesa"
VendorName "SIS"
BoardName "V64 S3 Trio"
BusID "PCI:0:11:0"
EndSection
Section "Monitor"
Identifier "L177W"
VendorName "LG"
ModelName "L177WS"
HorizSync 31.5 - 50
VertRefresh 40 - 90
ModeLine "1280x1024" 135.00 1280 1296 1440 1688 1024 1025 1028 1066 +hsync +vsync
ModeLine "1024x768" 78.75 1024 1040 1136 1342 768 769 772 800 +hsync +vsync
ModeLine "800x600" 49.50 800 816 896 1056 600 601 604 625 +hsync +vsync
Option "DPMS"
EndSection
Section "Screen"
Identifier "Default Screen"
Device "Silicon Integrated Systems [SiS] 5597 [SiS5582]"
Monitor "L177W"
DefaultColorDepth 24
#DefaultDepth 8
SubSection "Display"
Depth 1
Modes "1280x720" "1152x864" "1024x768" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 4
Modes "1280x720" "1152x864" "1024x768" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 8
Modes "1024x768" "1152x864" "1024x768" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 15
Modes "1280x720" "1152x864" "1024x768" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 16
Modes "1280x720" "1152x864" "1024x768" "800x600" "720x400" "640x480"
EndSubSection
SubSection "Display"
Depth 24
Modes "1280x720" "1152x864" "1024x768" "800x600" "720x400" "640x480"
EndSubSection
EndSection
Section "ServerLayout"
Identifier "Default Layout"
Screen "Default Screen"
InputDevice "Generic Keyboard"
InputDevice "USB Mouse" "CorePointer"
InputDevice "Serial Mouse" "CorePointer"
EndSection
Section "DRI"
Mode 0666
EndSection
No meu tem exatamente esse, mas ele já está com aceleração 3d e não consigo retirá-lo...
Se caso você ainda não tenha esse arquivo, crie um em branco, com o botão direito do mouse e faça a mesma operação.
Espero ter te ajudado,
abrços!