The audio can be carried over DVI to HDMI cable depending on the graphics card. For newer GPUs, you just need to set the HDMI audio device in the Windows Sound control panel. Older GPUs need to use a digital audio S/PDIF cable to connect from the PC to the graphics board's on board S/PDIF connector. Please contact your graphics board manufacturer if you have questions on supporting HDMI audio over DVI.
If your graphics card does not support HDMI audio over DVI or it does not have an S/PDIF cable built onto the card, you can use the motherboard's digital or analog audio connectors to output audio to the 3D TV or an external receiver. You will also need to disable the HDTV HDMI audio option from the NVIDIA Control Panel.
For more information on configuring your HDTV, please read Knowledge Base Article 2593.