Scenario 4: Nvidia videocard with HDMI

Nvidia’s audio-over-HDMI options are more limited than AMD’s. Most videocards based on new Nvidia GPUs (e.g., the GeForce 8000- and GT 200-series) support HDMI via an adapter and many have a S/PDIF input, so you can transfer both digital video and digital audio over a signal HDMI cable.

But if you’re not using a motherboard with an Nvidia chipset (e.g., nForce 750i, 790i, or 780i), you might not have the S/PDIF output header needed to make this connection. Even if your motherboard does have it, the card is capable of receiving only two channels of digital audio that can be sent over the HDMI cable—you can’t get any form of surround sound over HDMI this way, much less Dolby TrueHD or DTS-HD.

If you want simple stereo over HDMI, you’ll need to use your motherboard’s onboard audio (there’s no way to get digital audio from an add-in soundcard to a GeForce card with a S/PDIF input). Plug one end of the two-lead S/PDIF cable into the motherboard’s S/PDIF-out header. The header has three pins, but you’ll use only the two that are immediately adjacent to each other: One is labeled “Signal,” the other “Ground.” Under no circumstances should you connect the cable to the pin labeled “+5V”—doing so will fry your videocard. The distance between the pins should make this an unlikely event.

The next step in configuring an Nvidia card to send audio over HDMI is to connect the other end of the cable to the S/PDIF connector on the top of the videocard. The connector is typically placed right next to the power connectors; it might be covered by a rubber plug that you’ll need to remove.

At the risk of sounding like a broken record, this scenario limits you to two-channel audio. A superior solution is to use onboard audio (a stand-alone soundcard is even better) and establish analog connections between your PC and your A/V receiver. For a 5.1-channel configuration, you’ll need three cables with 1/8-inch stereo connectors on one end and left/right RCA plugs on the other. You’ll need one more cable for a 7.1-channel configuration.

Your A/V receiver must be outfitted with discrete analog inputs for front left/right, center, rear left/right, surround left/right (for 7.1-channel systems only), and low-frequency effects (i.e., a subwoofer input).

You’ll also need a software Blu-ray disc player, such as CyberLink’s PowerDVD 8, that’s capable of decoding Dolby TrueHD or DTS-HD and decompressing it to 7.1-channel LPCM.

External USB Audio

Here’s yet another solution for integrating your PC’s audio capabilities into your home-theater system: Use an external USB audio device. These won’t deliver multichannel sound over HDMI, but they’re dead simple to install: Plug the device into your PC’s USB port with one cable, plug it into your A/V receiver with another, and install the accompanying software.

Asus’s Xonar U1 USB Audio Station (www.asus.com) and Creative’s X-Fi Surround 5.1 (www.creative.com) are two examples of external USB audio devices. Both products use Dolby Digital Live to encode any audio signal to 5.1-channel Dolby Digital in real time. The audio is then output through a S/PDIF interface to your A/V receiver.

==>Part 1

From maximumpc.com