Asus P4B-FX - Manual (Page 29)

ASUS P4B-FX motherboard user guide 2-9
2.4.4 Connecting the CPU fan cable
When the fan, heatsink, and the retention mechanism are in place,
connect the CPU fan cable to the connector on the motherboard labeled
CPUFAN.
3. Push down the locks on the retention mechanism to secure the
heatsink and fan to the module base.
Figure 2-10 Fan and Retention Mechanism Installed and Locked
Figure 2-11 CPU Fan Connector
When secure, the retention locks should point to opposite directions.
CPU Fan Connector
(CPUFAN)