Well, if you have checked audio is enabled (strange you can't find it the Bios, but that mnual doesn't mention it other than to say 2 channel audio was an option) and have tried all and sundry drivers and have verified all the sound checks you did in post 1 and no sound, then maybe your sound chip is dead.

Here is an MSI mobo driver for that sound chip - try it if you like;

http://translate.google.ca/translate...%3Den%26sa%3DG