Asus P4-P5N9300 - Manual (Page 39)

3-7 ASUS P2-P5N9300/P4-P5N9300
3. CPU Fan connector (4-pin CPU_FAN)
The fan connector support cooling fans of 350mA~2000mA (24W max.).
Connect the fan cable to the fan connector on the motherboard, ensuring that
the black wire of each cable matches the ground pin of the connector.
DO NOT forget to connect the CPU fan cable to the CPU fan connector.
Insufficient air flow inside the system may damage the motherboard
components. It is not a jumper! DO NOT place a jumper cap on the CPU fan
connector!
We recommend that you connect a high-definition front panel audio module to
this connector to get the motherboard’s high-definition audio capability.
4. Back audio connector (20-1 pin Back_Audio Connector)