Try going to the link below, scroll down to G33M - On-board audio drivers, click on the + beside ViewDetails, then click on the icon next to "Download".
http://www.foxconnsupport.com/download.aspx?models=en-us0000319&category=C000000001&brand=en-us0000001&Series=en-us0000002&chipset=en-us0000111&keywords=&sort=