If you wanted to use an AC97 motherboard without front panel audio it was nessacery to put jumpers on the audio header to make the rear audio output work. On HDA audio to the front and rear outputs comes from seperate outputs on the audio codec. The pins that were previously used to loop back audio from the front are repurposed as connector-detect pins. It is up to software whether to disable the rear panel audio output when a connector[…]
