On the front of the Desktop case, the audio and usb ports have the function of connecting and transmitting audio and usb signals to the computer. This article will introduce the audio and USB ports and their signal cables.
1. Location, function of Audio and USB cables
Location: located on the inside front of the case.


Audio cable: transmit signal for the headphone port (usually green) and the microphone port (usually pink) to mainboard.
USB cable: transmit signal for USB port to mainboard.
2. Audio cable
There are 2 types of connection:
- AC’97 (Intel proposed in 1997)
- HD Audio (Intel proposed in 2004).
- Both include 9 pins and missing 8th pin.
Audio pins
Consists of 9 pins, usually denoted F_Audio, H_Audio, AAFP. It is very easy to plug in, not to be confused with any pins.
3. USB cable
Includes 9 pins: 2 pins with +5V, 4 data pins and 2 GND pins, 1 NC pin. USB cable is missing 9th pin.
USB cable pins
Consists of 9 pins, usually denoted USB, F_USB, Front USB. It is very easy to plug in, just avoid confusion with Front Panel pins.