Since you say nothing about which GNU/Linux distro you are using, and which desktop environment you are using, there is a question which must be asked. Do you really mean X, or do you mean the desktop environment you are using?
X is the standard interface between the kernel capabilities and the desktop environment.
There are many applications and applets which use X to display on screen. There are many desktop environments which use X to access the kernel capabilities. Examples are KDE, Gnome, Xfce, IceWM, and others.
So, please clarify your first question. Which distro are you using; which desktop environment you are using; do you really mean X or do you mean the desktop environment?
In re open graphics hardware, use
www.google.com/linux to explore that question.