Asus M3N78 SE - Manual (Page 20)

1-10 Chapter 1: Product introduction
2. Attach one end of the retention bracket to the retention module base.
1
3
4
5
2
3. Align the other end of the retention bracket (near the retention bracket lock) 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.
5. Connect the CPU fan cable to the connector on the motherboard labeled CPU_FAN.