Hello
I am writing today because after about 6 months this buzzing noise is driving me nuts. So I Googled and found lots of different sound problems with this board.
Anyways nothing worked for so I decided to start to try random things. After some time I found out that ASUS SOUND RADAR program was making this buzz. Just uninstall it and that bzzzzz will go away.
This buzz sound would only happen when I was playing a video game and the buzz would change infrequence as I moved my mouse.
I hope this fixes anyone else with this problem.