ASROCK B75 Pro3-M User Manual page 38

The front panel design may differ by chassis. A front panel module mainly
consists of power switch, reset switch, power LED, hard drive activity LED,
speaker and etc. When connecting your chassis front panel module to this
header, make sure the wire assignments and the pin assign-ments are
matched correctly.
Chassis Speaker Header
(4-pin SPEAKER 1)
(see p.15, No. 19)
Chassis and Power Fan Connectors
(4-pin CHA_FAN1)
(see p.15, No. 18)
(3-pin PWR_FAN1)
(see p.15, No. 1)
CPU Fan Connectors
(4-pin CPU_FAN1)
(see p.15, No. 4)
Though this motherboard provides 4-Pin CPU fan (Quiet Fan) support, the 3-Pin
CPU fan still can work successfully even without the fan speed control function.
If you plan to connect the 3-Pin CPU fan to the CPU fan connector on this
motherboard, please connect it to Pin 1-3.
(3-pin CPU_FAN2)
(see p.15, No. 5)
1
SPEAKER
DUMMY
+5V DUMMY
PWR_FAN_SPEED
+12V
GND
FAN_SPEED_CONTROL
CPU_FAN_SPEED
+12V
GND
1 2 3 4
GND
+12V
CPU_FAN_SPEED
38
Please connect the chassis
speaker to this header.
Please connect the fan cables
to the fan connectors and match
the black wire to the ground pin.
CHA_FAN1 supports Fan
Control.
Please connect the CPU fan
cable to the connector and
match the black wire to the
ground pin.
Pin 1-3 Connected
3-Pin Fan Installation