After installing Ubuntu 12.04 low screen resolution

After installing Ubuntu 12.04, I found that a 17-inch monitor is in mode1024x768. I looked in Preferences - Monitors and saw the two screens. First fake with the name "laptop" and the second real LG.
From a terminal prompt I ran:
$ xrandr
The utility showed me two video outputs: LVDS1 and VGA1. Need to disable LVDS1. Adding to the startup command:
$ xrandr - output LVDS1 - off - output VGA1 - auto
not satisfied. I would like to turn off this LVDS1 forever.
Changed in the /etc/default/grub line parameters are passed to the kernel:
I ran the following command:
$ sudo update-grub
Rebooted the system and found that at the moment fake video turned off and the screen resolution is set to the maximum for my monitor.