I have a Gigabyte G1 Assassin motherboard and it's supposed to have a good sound chip on board. I get this static/buzzing sound in my headphones when plugged into the headphone jacks. It's really noticeable between songs or when there's no sound input. I have the proper drivers installed and they are up to date. The computer is only a couple of months old.
I also use a Logitech USB gaming headset and never have problems with it, it's a little old now and the earphone cushion is falling apart. USB just seems way better, but it's not taking advantage of the sound card is it? I have been thinking about getting a nice headset that uses the mini audio jacks but if it's going to buzz and have this white noise static then I don't want to.
Another thing I noticed is that when watching Netflix with my USB headset sometimes the Netflix sound is very faint compared to other sounds. I would be playing SC2 on one monitor and listening/watching South Park on the other and I turn the sound full blast and can barely hear South Park but SC2 is super loud so I turn it down in game to 2% or something. Other times I can watch movies by themselves on Netflix with my USB headset and it works great. Maybe it's certain videos or something...
The buzzing sound is probably electromagnetic interference being picked up by the long cable that runs from the mobo to the front of your case. The signal in this cable is analog, and thus susceptible to stray magnetic fields from fans and such. When you use the USB headset, the audio signal is transmitted digitally and is thus not really prone to interference. It only becomes analog outside the case inside the Logitech dongle.
My suggestion is to plug your headphones directly into the motherboard.
Thanks for your input shark. That might be a likely solution for anyone else who has the same problem. I fixed it differently however. I had my speaker system plugged into the motherboard and the settings in playback for my sound card was picking up 5.1 channel surround. My headphones were just 2 channel stereo. I think the buzzing and what not was feedback from these channels my headphones couldn't handle. All I know is that I changed my settings to stereo and the problem disappeared.