Buzzing Sound and Onboard Audio

[blckman]

Okay guys. I just watched Friday Night Lights on my Toshiba 51H83 from my computer. I did it via a dongle from my 9600 Nvidia to component in the back of the 51H83. The only problem is that when I hooked up the sound from the onboard sound on the motherboard to the Toshiba I get a buzzing noise coming from the TV. What gives and why? Is there any way to resolve this? I used the Y cable/splitter from the sound card(green connection) and used adapters to hook the cables to the back of the television(red and white). I'm getting sound and it is great, but that buzzing noise does not stop. Do I need a separate sound card to get rid of the buzzing sound or what? I mean everything is working fine. I do have a phillips sound card that has spdif out/in cords to go along with it. Do I need to install the soundcard to get rid of that annoying buzzing sound coming from the television? Is the onboard sound that bad coming from the motherboard? Can some of you experts help resolve this issue? Thanks guys.