I had issues with crashes with my GTX580 and Realtek on board sound, found out the solution was to completely remove the nvidia drivers (inc HD audio) and then reinstall via custom and deselect HD Audio driver and select perform clean install. Once installed go into Device Manager, right click your graphics card and select properties and make note of the PCI bus number, then go to System Devices and find the High Definition Audio Controller that shared the same PCI bus number and disable it.
