My case has an audio cable with two connectors on it clearly labeled "AZALIA" (codename for HD Audio according to the wiki) and "AC'97". I had AZALIA connected to the motherboard AAFP connector. The ASUS motherboard has a BIOS setting to toggle between the default HD Audio setting (which is what I have set) and legacy AC'97 mode.
My case has an audio cable with two connectors on it clearly labeled "AZALIA" (codename for HD Audio according to the wiki) and "AC'97". I had AZALIA connected to the motherboard AAFP connector. The ASUS motherboard has a BIOS setting to toggle between the default HD Audio setting (which is what I have set) and legacy AC'97 mode.