There are two different standards for the on-board audio header pinout for mainboards and audio adapter cards - AC97 and the more recent Hi-Definition Audio (HDA). The two standards are incompatible.

Front panel audio ports are connected to the mainboard (or audio adapter card) via a cable and header plug. The correct type of cable and front panel PCB must be used and the correct matching driver must also be used.

HDA allows the driver to detect jack insertion and removal. This allows a driver to automatically route audio output to the correct port. For instance, if you have speaker connected to the rear audio output port (green) and then connect headphones to the front (green) audio output socket, the driver can automatically re-route the audio stream to your headphones and cut-off the audio to the speakers (or may prompt you to ask what you want to do).

HDA also allows a driver to route different signals to different jack sockets, thus allowing multi-function jack sockets which can be used for different purposes (e.g. using line-in and microphone jack sockets as speaker outputs to enable 5-1 surround sound speakers to be connected).

Some audio drivers can be configured by the user for either an AC97 type cable+front-panel or an HDA cable+front-panel. Other drivers exist in separate versions, one version for AC97 and another driver version for HDA - you must install the correct one depending on which type of front panel and cable you have fitted.

The RealTek driver when first installed, by default, is configured for an HDA-compatible front header panel.

0. Double-click the RealTek HD Audio Manager system tray icon (see Fig. 1 above).
0. Click the Audio I/O tab (see Fig. 2 below).
0. Click the spanner next to the Analog option.
0. If the 'Disable front panel jack detection' option is present, tick the tick box and then click the OK button. If the 'AC97 Front panel support' option is present, untick the tick box and then click the OK button.
0. Now insert the jack plug of either a microphone or headphones into the corresponding front panel socket of your computer.
0. If you now see the message 'Information: A jack has been plugged in' then you do not need to change this setting as your system has a HDA-compatible front panel.
0. If you do not see this message or your internal speakers are not working, then click on the small folder icon again and tick the 'Disable front panel jack detection' tick box.

Fig. 2 Disable front panel jack detection option