If both the driver provided by your computer manufacturer and the generic driver on our site are having the same behavior, the problem could be related to the operating system you have installed. What is the operating system being used?
I'm using Windows 7 Home Premium x64.
You can try with the test driver that is posted here:
Also confirm that there are no conflicts on the Device Manager after loading any of the drivers. Also you could try with a fresh operating system installation in a separate drive.
If the issue persists, check with your motherboard manufacturer for further troubleshooting on the audio controller of this system board.