There are actually 3 versions of your motherboard, viz 1.0, 2.0 and 3.3. In each case, the audio solution is provided by Realtek. You say that you have got the latest driver installed. Did you obtain it directly from Realtek or from Gigabyte? The version from Gigabyte is an old version, R1.87 whereas the version from Realtek themselves is R1.90 and is dated 2008/3/31. I provide a link to the appropriate Realtek webpage for your convenience. Please note that you may need to fully uninstall an older driver before installing a newer version and that sometimes it is necessary to install it twice in succession.
Dwarf
Realtek