I don't know if this will be of any use to you, but I recently bought a new custom built computer and couldn't get any noise from the front earphone socket. I hadn't realized that there were two options in the sound section reached through the control panel.
My question to them:
I'm unable to get any sound out of the front ear phone socket when using either of the two CD players (DVD rom drives). If I plug in the ear phones and launch Realtek Audio I/O tab, go to the drop down box, select headphones and click the button I DO get the demo noise through my earphones. When I plug my speakers into the green socket of the Creative SB card the speakers play OK.
So I'm unable to hear any sound other than the Creative SB demo from the front earphone socket.
Their reply: (Which worked)
The speakers issue, some of the creative cards do not support the front audio jacks. If you switch the default sound device to realtek in the sound
options you should get the CD player and DVD etc through the front earphone socket.
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When I want to revert back I have to do a reversal of what they suggested