I just bought a new PC and it has a EVGA superclocked Nvidia GFX 560 Ti and I have a Sharp Aquos LC32D41U 32 HDTV. The LC32D41U only supports PC through its DVI connector (for some reason they don't let PCs use HDMI).
I hooked up the DVI cable to one of the two DVI females on the graphics card. I have an audio cable connecting my DVI audio from my HDTV to the green colored motherboard audio jack in the back. No other color works but green.
When in 3D mode it gives the monitor's speaker a certain humm or buzz depending on the graphics intensity going from a high pitch squeal (light intensity reaching 3900 FPS) to a low humm (high intensity DX10 reaching 50 FPS).
When not using a 3D application there seems to be super faint noticeable high pitch buzz, that is only heard when the TV volume is really high.
Unplugging the audio jack stops the noise, so I don't think its with the DVI cable itself.
My monitor is actually a HDTV and it has a 2 prong power cord anyways but I still plugged it into a completely different socket and the sound persisted. I then attempted to make a shield from alumnium foil and I could not get the sound to stop. Finally I played around with the wires and still the sound. Now I have the EVGA connected to my HDTV using DVI and I have a DIV audio cable from my HDTV to the line-out on the motherboard. You would think disconnecting the DVI would leave the sound but get rid of the picture but the humming stops when I disconnect the DVI. This leads me to believe the card is somehow trying to giving the DVI cable interference down the line. It's a expensive heavy & thick cable DVI cable with a male single link DVI-D end.
Installed the lastest onboard sound driver, retarted..same problems. Decided to reinstall the newest nvidia drivers, same problem. Decided to uninstall everything nvidia, restart, and now I can't run anything 3d to test (haha) as its generic driver. Reinstalled just the display drivers, not the audio....same problems.. Then I disabled all each audio device in device manager one by one and test, even with all audio devices disabled the sound persisted. Keep in mind this sound comes through even when I have the windows (software) volumne muted.
I found another male to male 3.5 mm stereo jack and tried it, the sound still remains. Because the sound doesn't exist without the 3.5 mm jack by itself nor does it exist with the DVI by itself I am thinking this is more and more a ground loop issue. I might pickup a ground loop isolator later on...