I would recommend you to test your computer without the audio front panel being connected, try to test the system that way for a while and see if the issue persists.
If the problem is resolved by removing the audio front panel, it might be a compatibility issue with the front panel connected, check if the panel is validated for AC97 audio or in the other case, for HD audio. (You may need to check that information with the front panel manufacturer or the chassis manufacturer)
If the problem continues without the audio front panel connected, try the motherboard out of the chassis, placed on a non-conductive surface like a newspaper, a magazine or something similar, this would be to isolate the problem from being a grounding issue. Furthermore, the issue could be also related to a software corruption, so you may need to try another hard drive and test a fresh operating system installation.