Asus P5K Premium/WiFi-AP - Manual (Page 62)

2-36 Chapter 2: Hardware information
2.8 Installing the optional fans
Install the optional fan only if you are using a passive cooler or a water cooler.
Installing the optional fan with an active CPU cooler can interfere with the
airflow and destabilize the system.
1. Position the fan above the pipe
and heatsink assembly.
2. Fit the fan to the grooved edge of
the heatsink.
3. Carefully push down the fan until
it snugly fits the heatsink, then
connect the fan cable.