Asus CROSSHAIR IV EXTREME User Manual page 38

2. Attach one end of the retention
bracket to the retention module
base.
3. Align the other end of the retention
bracket to the retention module
base. A clicking sound denotes that
the retention bracket is in place.
Ensure that the fan and heatsink
assembly perfectly fits the
retention mechanism module
base, otherwise you cannot snap
the retention bracket in place.
4. Push down the retention bracket
lock on the retention mechanism to
secure the heatsink and fan to the
module base.
2-12 Chapter 2: Hardware information