Most servers are run without a GUI, although some administrators will install the GNOME desktop on a server in order to perform some tasks. By changing the default runlevel, you can still use X windows when needed, but by default, the server will boot to the text mode login screen, thereby saving server resources.
Change the default runlevel from 5 to 3
Runlevel 3 starts most services and provides the text mode login. Runlevel 5 automatically starts X in addition to the mutliuser services provided by runlevel 3.
Edit the /etc/inittab file, change any references from 5 to 3, and reboot the computer.
Starting X from the command line
Log in to the server using a user account other than root. At the prompt, type the following: