[SOLVED] Connecting front panel audio to ASUS M4A87TD/USB3

Jan 3, 2021
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I am having trouble connecting the front panel audio of my PC case (unknown manufacturer) to a ASUS M4A87TD/USB3 mainboard.
The front panel wires have the following configuration:
Code:
FP1 EAR GND ■■■■───────────── (black)
FP2 EAR RGT ■■■■──────┬────── (green)
FP3 EAR RGT ■■■■──────┘       (green)
FP4 EAR LFT ■■■■──────┬────── (blue)
FP5 EAR LFT ■■■■──────┘       (blue)
FP6 MIC GND ■■■■───────────── (purple)
FP7 MIC IN  ■■■■──────┬────── (yellow)
FP8 MIC IN  ■■■■──────┘       (yellow)

Due to the two ground wires I am assuming that the panel uses AC97 (I switched the BIOS settings accordingly):
Code:
AC97 definition:                     My wiring:
     MIC - 1  2 - AUD_GND            FP8 (MIC IN)  - 1  2 - FP6 (MIC GND)
MIC_BIAS - 3  4 - AUD_GND            FP7 (MIC IN)  - 3  4 - FP1 (EAR GND)
FP_OUT_R - 5  6 - FP_RETURN_R        FP2 (EAR RGT) - 5  6 - FP3 (EAR RGT)
  AUD_5V - 7  x                                 NC - 7  x
FP_OUT_L - 9 10 - FP_RETURN_L        FP4 (EAR LFT) - 9 10 - FP5 (EAR LFT)

Intel HD definition:
    PORT1L - 1  2 - GND          
    PORT1R - 3  4 - PRESENCE#    
    PORT2R - 5  6 - SENSE1_RETUR 
SENSE_SEND - 7  x                
    PORT2L - 9 10 - SENSE2_RETUR

Any ideas what went wrong?