How do I disable Onboard sound?

Hi again folks.

I'm having problems with Shogun 2 total war with regards the mss32.dll errors, which I have been told are related to the Miles fast sound system files used by the game and windows.  I have been told to disable the onboard sound (as I have a creative SB titanium sound card installed) because it maybe conflicting with the sound cards.  I have disabled all of the realtek options via device manager and msconfig but would like to know how to disable through BIOS.

The only option I can see is HD Sound enabled in the BIOS.  Does this refer to the onboard sound card only? In which case I will go ahead and disable it.

Any help is appreciated.