Cpu_Fan1, Sys_Fan1~2: Fan Connectors - MSI B450M PRO-VDH Handbuch

CPU_FAN1, SYS_FAN1~2: Fan Connectors

Fan connectors can be classified as PWM (Pulse Width Modulation) Mode or DC
Mode. PWM Mode fan connectors provide constant 12V output and adjust fan speed
with speed control signal. DC Mode fan connectors control fan speed by changing
voltage. When you plug a 3-pin (Non-PWM) fan to a fan connector in PWM mode, the
fan speed will always maintain at 100%, which might create a lot of noise. You can
follow the instruction below to adjust the fan connector to PWM or DC Mode.
Default PWM Mode
fan connector
Switching fan mode and adjusting fan speed
You can switch between PWM mode and DC mode and adjust fan speed in BIOS >
HARDWARE MONITOR.
Select PWM mode or DC mode
Important
Make sure fans are working properly after switching the PWM/ DC mode.
Pin definition of fan connectors
PWM Mode pin definition
1 Ground
3 Sense
14
Overview of Components
1
CPU_FAN1
There are gradient points of the fan speed that allow you to
adjust fan speed in relation to CPU temperature.
2 +12V
4 Speed Control Signal
Default DC Mode fan
connector
DC Mode pin definition
1 Ground
3 Sense
1
SYS_FAN1/ 2
2 Voltage Control
4 NC