Some of the ASUS MBDs use an ASUS unique Realtec chip (ALC1200) The
driver is usually available on the ASUS web site if this is the case.
The default windows drivers may not include some of the needed Realtec
modules such as a sound mixer module.
(I recently ran into this on an ASUS M4A 79 Deluxe MBD.
Further, there have been various problems dealing with the 8800 drivers.
If that isn't enough, some games require that you obtain the last
microsoft DX 9c update, and install it over the DX10/11 system, in order
to update some of the DX 9c modules.

Some games, such as Crysis, were not completely debugged in DX10, and
work better if forced into DX9 mode.

On 5/5/2010 8:08 PM, undisclosed wrote:
Not much help, I know, but this has just happened to me too. Spooky.

Windows 7 x64
Q6700
8800GT
Asus Maxmius Extreme
6GB DDR3