Manually closed old game on computer, and headphones have been buzzing since...?

[PlushyG]

I have restarted the PC several times, and have disabled the other audio playback devices (not via devmgr, but via the sound control panel)... but the problem remains

In other similar threads, I've seen people mention overclocking could be an issue --- I have not overclocked my pc.

What can I do?

 

[rgd1101]

and unplug the headphone from the computer?