Asus P1-AH2 - Manual (Page 32)

2-14 Chapter 2: Basic installation
2.10 Installing an optical drive
Follow these steps to install an optical drive:
1. Turn the storage drive assembly upside down with the 3.5-inch bay on
top of the 5.25-inch bay.
2. Insert the optical drive upside down to the 5.25-inch bay, then secure
it with two screws on both sides.
3. Turn the storage drive assembly, insert the hard disk drive upside
down to the 3.5-inch bay, then secure it with two screws on both
sides.