Ubuntu LogoComputer having old hardware or incompatible hardware like SIS,VIA is not fully compatible with Ubuntu Linux. This result the maximum resolution of Ubuntu to be 800×600. You can force the resolution of 1024×768 by editing xorg.conf file present in X11 folder.

First of all start “terminal” and pass this code “gksudo gedit etc/X11/xorg.conf”, this will open xorg.conf in Gedit . Now replace existing code with this one ,

Section “Device”
Identifier    “Configured Video Device”

Section “Monitor”
Identifier    “Configured Monitor”
HorizSync       30.0 – 62.0
VertRefresh     50.0 – 70.0

Section “Screen”
Identifier    “Default Screen”
Monitor        “Configured Monitor”
Device        “Configured Video Device”
DefaultDepth    24
SubSection “Display”
Depth    24
Modes     “1024×768” “800×600”

Save it & restart your computer and you will be able to switch to 1024×768 resolution.