Linux kill X server

Got frozen X and need to kill X server on your Linux system, just press Ctrl+Alt+Backspace key on your keyboard and your Linux X server will automatically kill and restart without any question ask.

or you can open Linux terminal su- to have root privileges and type in killall
To kill Gnome desktop type in

[root@serverc ~]# killall gdm

To kill KDE desktop type in
[root@serverc ~]# killall kdm