cause trouble when AC'97 front-panel dongles are used with HDA motherboards and vice versa. An AC'97 dongle returns audio on pins 6 and 10 rather than digital plug sensing signals. Consequently, a loud audio passage may cause a HDA motherboard with a AC'97 dongle believe headphones and microphones are being plugged and unplugged hundreds of times per second. An AC'97 motherboard with an HDA dongle will route the AC'97 5 V audio supply (pin 7; silence) to the speakers instead of the desired left and right audio signals. To avoid this, some motherboards allow choosing between HDA and AC'97 front panels in the BIOS. Even though the actual audio hardware is HD Audio, the BIOS can be manipulated to allow the use of an AC'97 front panel. Likewise, some modern enclosures have both an "AC'97" and an "HDA" plug at the end of the front-panel audio cable. See also Sound chip References External links https://web.archive.org/web/20121202194339/http://www.intel.com/design/chipsets/hdaudio.htm https://web.archive.org/web/20110310072114/http://www.intel.com/standards/hdaudio High Definition Audio Specification 1.0a (June 17, 2010) Motherboard/Sound-cards connectors pinout specifications Developer Education Resource: High Definition Audio for the Digital Home Computer hardware standards High Definition Audio Sound cards