My cousin was able to fix a crash issue on his Gigabyte Z77X-UD5H by using the sound driver from the realtek website, not gigabyte:
http://www.realtek.com.tw/downloads/downloadsView.aspx?Langid=1&PNid=14&PFid=24&Level=4&Conn=3&DownTypeID=3&GetDown=false
Also, people on TweakTown are saying...