Intel P31 User Manual page 27

Without this connector might cause system unstable because the power supply can not
provide sufficient current for system.
(3) PS/2 Mouse & PS/2 Keyboard Connector: KB
The connectors are for PS/2 keyboard and PS/2 Mouse input devices.
(4) USB Port connector: from USB1, UL1
The connectors are 4-pin connectors that connect USB devices with the 400Mbit / sec
data transfer rate to the system board.
(5) RJ45 LAN Port connector: from UL1
This connector is standard RJ45 over USB connectors for Network and USB devices
connection. The UL2 support r 10MB/100MB/1G B/s data transfer rate
(6) Audio Line-In, Lin -Out, MIC Connector: AUDIO
These Connectors are 6 Phone-Jack for LINE-OUT, LINE-IN, MIC audio connections.
Line-in : (BLUE)
Line-out : (GREEN)
MIC : (PINK)
(7) Serial Port (9-pin): COM1
COM1 is a 9-pin RS232 serial port connector.
(8) Floppy drive Connector (34-pin block): FLOPPY
This connector supports the provided floppy drive ribbon cable. After connecting the
single plug end to motherboard, connect the two plugs at other end to the floppy drives.
Audio input to sound chip
Audio output to speaker
Microphone Connector
PS2 Mouse
Clear CMOS Button
PS2 Keyboard
SPDIF
Out
23
Gigabit LAN
Connector
USB
Serial Port Connector
Line -In(Blue)
Line Out(Green)
MIC-In（Pink）
USB