Read the manual. If you don't have a copy go to Asus support and download.
It will tell you how to set the bios RAM speeds.
No need to OC. Since it is an Asus board the bios will probably list a default, Auto, and manual setting. A sub menu of manual will list the optional MHz susch as 10xx,13xx, 16xx etc.
The manual will show you pics of what to look for.
Use link below. Top of that page left use Auto detect moboard or drop curtains on top right. Then select OS then it will give you a list of drivers
and a list of Manuals.
Mike ASUSTeK Computer Inc.-Support-