That feature just overclocks the onboard (integrated) graphics. There is a software you can download from ASUS (for some models). Or you can just do it manually in the BIOS/UEFI (better approach).
On your model, there is a physical switch on the motherboard located above the 24 Pin power connector that says GPU Boost. Flick the switch and the board will do some OC'ing for you on the integrated graphics when you boot up again (flick the switch while computer is off, as recommended by ASUS).
If you use discrete video cards, this is useless to you.