MSI X370 SLI PLUS User Manual - Page 34

CPU_FAN1, PUMP_FAN1, SYS_FAN1~4: 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 connectors 1 CPU_FAN1 1 PUMP_FAN1 Default DC Mode fan connectors 1 1 SYS_FAN1/ SYS_FAN3/ SYS_FAN4 SYS_FAN2 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 There are gradient points of the fan speed that allow you to adjust fan speed in relation to CPU temperature. Important Make sure fans are working properly after switching the PWM/ DC mode. Pin definition of fan connectors PWM Mode pin definition 1 Ground 2 +12V 3 Sense 4 Speed Control Signal DC Mode pin definition 1 Ground 2 Voltage Control 3 Sense 4 NC 34 Overview of Components