Asus AP1720-E2 - Manual (Page 84)

Chapter 3: Installation options 3-8
6. Push the power supply to the
power supply cage until the metal
brackets and the chassis screw
holes align.
5. Push the power supply halfway
to the power supply cage, then
attached the a metal bracket on
each side of the power supply
with two screws.
7. Secure the power supply to the
chassis with two screws on each
metal bracket.