MSI B450-A PRO 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. However, with autodetection mode fan connectors, the system will auto detect the fan mode. Default PWM Mode fan connectors 1 1 CPU_FAN1 PUMP_FAN1 Default DC Mode fan connectors 1 1 SYS_FAN1/ SYS_FAN2 SYS_FAN3/ SYS_FAN4 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 Important y You can switch between PWM mode and DC mode and adjust fan speed in BIOS > HARDWARE MONITOR. y Make sure fans are working properly after switching the PWM/ DC mode. JCOM1: Serial Port Connector This connector allows you to connect the optional serial port with bracket. 2 10 1 9 1 DCD 2 SIN 3 SOUT 4 DTR 5 Ground 6 DSR 7 RTS 8 CTS 9 RI 10 No Pin 34 Overview of Components