Re: Is there a way to disable void HDMI audio from DVI output of 8400GS?
I have the same problem.
But there is a thread already describing this problem (I'm too lazy to search now).
Moreover, I had to mute the flat panel completely, because when X is starting I hear a lot of noise coming from the speakers (both in Windows and Linux).
Then the noise dies and there is no way to force analog audio or use the speakers in any way.
The problem appeared around 16x.xx drivers IIRC. There is more info in that other thread.