TV is a Philips 42PFL3603D/F7, Software is latest Status 1.15
Computer has an Intel DG43NB board with on-board DVI and 3.5 mm Audio Jack
Video - Connection is with DVI to HDMI cable to HDMI3 input at the TV
Audio Connection is a Y-RCA Cable from 3.5 mm Line Out to DVI Audio In for HDMI3

Video is OK, but no Sound. When I pull the HDMI cable and leave the RCA-Y cable in, restart the computer I have sound, but no video. As soon as I plug in the HDMI, video is there, but no sound.

The same computer and setup works perfectly with a Samsung Synchmaster LCD TV having both, video and sound, only the Philips is trouble. Obviously the Philips gets confused from any noise on the HDMI input and ignores the RCA connection. The Philips software has no possibility to ignore HDMI audio in and therefore to take the RCA. As per the manual, HDMI3 should work with the DVI Audio in for HDMI3, but it doesn´t. Only when the HDMI cable is pulled.

As the mainboard is no HDMI but DVI only there is no possibility in the BIOS to disable any HDMI audio. I can only disable all audio, but that wont help either.

Any ideas, other than working with the Samsung instead of the Philips?