I have a similar problem with an amd board. It has the sis 7012 sound and then a cmedia 9738 onboard sound chip. I think that the sound chip has to be supported to use the gnome or kmixer. I get sound but the mixers don't work. I run kde and use th "arts control" to adjust the volume. I also have a board with the 7012 audio, but the onboard soundchip is a avance logic. This setup works with both mixers. I can even record with the gnome recorder in gnome only.
You should check the alsa site for infromation on your sound chip.
http://www.alsa-project.org/
They will probably eventually have drivers for the sound chips.