Asus P9D WS - Manual (Page 40)

2-22 Chapter 2: Hardware information
Chapter 2
2. Chassis Fan control setting (3-pin CHAFAN_SEL)
These jumpers allow you to switch for fan pin selection. The CHAFAN_SEL jumper is for
the front fans and rear fans control. Set to pins 1–2 when using 3-pin fans or pins 2–3
when using 4-pin fans.
• If you use a 4-pin fan but set the jumper to pin 1-2, the fan you installed may not work.
• If you use a 3-pin fan but set the jumper for a 4-pin fan, the fan control will not work and
the fan you installed will always run at full speed.