Asus CROSSHAIR IV EXTREME User Manual page 61

6. CPU, chassis, and optional fan connectors
(4-pin CPU_FAN, 4-pin PWR_FAN, 4-pin CHA_FAN1–3, 4-pin OPT_FAN1–3)
The fan connectors support cooling fans of 350 mA–2000 mA (24 W max.)
or a total of 1 A–7 A (84 W max.) at +12V. Connect the fan cables to the fan
connectors on the motherboard, ensuring that the black wire of each cable
matches the ground pin of the connector.
DO NOT forget to connect the fan cables to the fan connectors. Insufficient air
flow inside the system may damage the motherboard components. These are
not jumpers! DO NOT place jumper caps on the fan connectors!
If you install two VGA cards, we recommend that you plug the chassis fan
cable to the motherboard connector labeled OPT_FAN1/2/3 for better thermal
environment.
ROG Crosshair IV Formula 2-35