This is the most misunderstood driver. ASUS’s ATKACPI driver (also called "ATK Hotkey Utility") controls the Fn keys (brightness, volume, WiFi toggle).
The K53S is a classic "Hackintosh" and "Linux workhorse" laptop because of its robust build. The driver situation reveals three key phases of its life: asus k53s driver best
To get the "best" performance, never just update over an old driver. Use the Clean Install method, particularly for Graphics. This is the most misunderstood driver