I have some Dell OptiPlex 3010 DT PCs. One has the I3 CPU and one with the I5 CPU. Mobos are 100% identical though. I will try the LayoutID 13 (0D) - SwitchMode.
Edit: The switchmode works. It switches the Audio output automatically from front speakers to headphones when I plug in the mini jack to their respective outputs. I did not have any microphone to test with but I connected my headset into the MIC input in the back (Pink connector) and shouted into the headset. The meter under input devices moved, however the port is detected/listed as LINE IN. When I connect to the Line IN (Blue connector) it still says Line IN but the Input Volume meter does not respond to any sound Input. When I connect to the front Microphone connector in front of the cabinet it still says Line IN but the input volume meter does not respond to any sound input. I guess it does not detect any changes when the mini jack gets plugged in and therfore does not switch to the Front Mic connector. The same may be the case with the rear Line IN (Blue) connector. But what puzzels me is that the pink MIC connector works but lists as Line IN and still seems to respond fine to a weak MIC Level input even though it is listed as LINE IN.
However nothing of this is any issue for me. I was quite happy with the first "manual" kext that made the soundcard work and enabled the use of the Headphone and the Speaker outputs even though they had to be selected manually. In any case I would like to record audio or use a microphone I would use a USB Microphone for mic level input recording or an external stand alone studio soundcard for line in level input audio recording.