Asus AP140R-E1 - Manual (Page 20)

Chapter 2: Hardware setup 2-6
2. Hold down the heatsink lightly
and twist each of the four screws
with a Philips (cross) screwdriver
just enough to attach the heatsink
to the motherboard.
3. When the four screws are
attached, tighten them one by one
to completely secure the heatsink.
2.2.3 Installing the CPU heatsink
To install the CPU heatsink:
1. Carefully place the heatsink on
top of the installed CPU.