I'm using the onboard sound on my Asus P5B-E and I hear weird buzzing whenever I use my headphones plugged into the front audio jack (on a coolermaster centurion 5 if it matters). The front panel is plugged in using an HD audio connector
The buzzing is definitely effected by whats happening on the screen. For example, it will be quiet, but when I scroll a browser window, it is louder during the scroll. I don't have any problems using the rear jack.
Any ideas on what can cause this or steps to troubleshoot?
Do you have any USB devices hooked up to the front panel as well? I have the same problem with my case (Antec TX-1050B) when I have my Logitech G15 backlit keyboard hooked up to the front panel. I think its a problem with the signal wires for the audio and USB not being well shielded from each other. Whenever a device sends data and/or power through the USB bus I get noise (which is all the time if I have the backlighting turned on). My solution was to hook up the keyboard to the back of the motherboard rather than use the front panel.