Best way to get audio out on the 9800GX2 HDMI?

Ive been using the HDMI of my 9800GX2 with some external speakers. Id like to get pipe the audio through the HDMI cable like I did when I had my ATi Radeon 4870.

But Ive looked and only Spdif that my motherboard has is an RCA output on the back panel, there is absolutly nothing on the board. Can I make an adapter to go from the RCA output on the back of the board to the input on the 9800GX2?

Yep. You just need to figure out which pin is ground.

Thanks for the reply.

Im pretty sure I know which is ground, I got the cable that comes with the EVGA 9800GX2 for audio in, and it has one black wire and I belive one white wire. So I assumed black was ground.

Will it screw up anything if I happen to be wrong and plug it in backwards? Ive already made the adapter with a RCA plug and fan header, so I can just plug the wire that came with the card in to it.

It shouldn't screw up anything on your PC as the signal is just being sent over wires no matter if they are reversed or not. The signal is just passing through the graphics card...it doesn't go through any active components. If anything it might do something to the audio equipment it is plugged into, but I seriously doubt it.

Black should be ground, and the outer ring on the spdif should also be ground.