I feel that there could be any of the reason among three..
1. Volume setting in LINUX. look out kmixer sort of thing..
or
2. Buggy driver :: In this case look for its driver and try to install a new one.
or
3. May be wrong prediction of the Hardware by OS. You can disable your onboard audio from bios then start linux, it will ask you to keep the config of the removed hardware.. say yes.. the again restart system.. .. and shutdown.. now again enable the audio from bios , now start system, OS will ask to configur : say YES.
May be that way it can be loaded with right module !
LITTLE unscientific though !