Détecter la carte graphique :
lspci | grep 'VGA compatible controller'

Redémarrer le serveur graphique :
sudo /etc/init.d/mdm restart

Aussi : Ctrl + Alt + Backspace

Sauvegarder le fichier de configuration :
sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf.backup

$ lspci | grep "VGA compatible controller"
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
01:00.0 VGA compatible controller: NVIDIA Corporation GF108M [GeForce GT 630M] (rev a1)

sudo lshw -enable pci -class display

$ sudo lshw -enable pci -class display
PCI (sysfs)

  *-display
       description: VGA compatible controller
       product: GF108M [GeForce GT 630M]
       vendor: NVIDIA Corporation
       physical id: 0
       bus info: pci@0000:01:00.0
       version: a1
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress vga_controller bus_master cap_list rom
       configuration: driver=nouveau latency=0
       resources: irq:42 memory:db000000-dbffffff memory:c0000000-cfffffff memory:d0000000-d1ffffff ioport:d000(size=128) memory:dc000000-dc07ffff
  *-display
       description: VGA compatible controller
       product: 2nd Generation Core Processor Family Integrated Graphics Controller
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 09
       width: 64 bits
       clock: 33MHz
       capabilities: msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:43 memory:dc400000-dc7fffff memory:b0000000-bfffffff ioport:e000(size=64)

Remarque : il est arrivé que Cinnamon plante –> Aller alors dans /System settings/administration/device manager/ et selectionner une autre carte graphique