Asus PCH-DL - Manual (Page 26)

2-8 Chapter 2: Hardware information
The Intel ® Xeon™ processors require an Intel certified heatsink and fan
assembly to ensure optimum thermal condition and performance.
When you buy a boxed Intel CPU, the package includes the heatsink, fan,
retention brackets, screws, thermal grease, installation manual, and other
items that are necessary for CPU installation.
2.3.3 Installing the CPU heatsink and fan
1. With the motherboard on a flat stable surface (such as a table), place
the thermal plate underneath a CPU socket, matching the standoffs on
the plate with the four holes around the CPU socket.
The figure below shows the corresponding matches of the
motherboard holes and standoffs.
1. Perform the installation steps 1 to 3 in this section before
installing you motherboard into the chassis.
2. Make sure that you have applied the thermal grease to the top of
the CPU before installing the heatsink and fan.
3. Refer to the installation manual that came with the CPU package
for details on heatsink/fan assembly and installation.
To install the CPU heatsink and fan:
Standoff Motherboard hole
CPU
thermal
plate