In device manager, if it shows under sound section that "ATI High Definition Audio Device" is not working well after a successful video card driver
installation, you should update your motherboard bios. Also, disable any unused ports such as serial and/or parallel in the bios after update. (Or now if no update.)
Also install audio driver for you board. http://www.asrock.com/mb/download.as...l=N68-S&o=Win7
Right click the speaker icon near the time in system tray. Choose playback devices. You can right click in there and set to show hidden devices.
Right click on the one you want and choose to set it as default device.