Buzzing/ringing sound from front panel audio jack.

Hey guys,

When connected through the front panel audio jack of my computer, my headphones pick up this really irritating ringing/buzzing/static noise. I assume it's hardware related but it seems like it could also be connected to software somehow because the pitch and severity of the sound varies as I perform different tasks (eg: scrolling pages up and down, transferring files from one location to another, opening certain programs etc...).

Audio from the rear jack is fine. I know it isn't a problem with my headphones, I'm listening with Audio Technica ATH-M50's which sound perfect with other devices. I've also tested the front the jack with various other speakers, headphones and ear buds and the same ringing is produced no matter what is connected. The sound is present both when using on board audio and my Asus Xonar DG card (one of the reasons I bought the card was to eliminate the buzzing). I've altered all the audio settings I can think of with no results. At first I thought the sound may have been caused by the front panel audio cable touching the video card or motherboard so I moved it as far away from other components as possible to no avail.

Does anyone know what may be causing this?

System Specs:
Seagate Barracuda 1TB ST31000528AS
Samsung SH-S223C SATA DVDRW Drive
Powercolor Radeon HD5770
1GB Mushkin 996768 Silverline PC3-10666 (2x2GB)
DDR3 Intel Core i5 760
Coolermaster Hyper 212+
ASRock H55M-L Motherboard
Asus Xonar DG sound card
Aywun A-1 Game series case

Thanks for your time.