Small 2 pin connector in GTX 260/280 9800?

Ok this might be a stupid question, but I just purchased a GTX 260 card and it comes with a little 2 wire cable. On the card the connector is right next to the 2 power plugs. I looked in the manual and on eVGA's site and can't find anything. I see that it is on the 260/280 and some of the 9800 cards. What is this thing?
 
Hi its aHDMI_ SPDIF cable it plugs into the motherboard somewhere i beleive if the MOBO supports it, black end to MOBO on the SPDIF header (yea really :lol: ) while end either two or three pin goes to Card. Make sure you get this right or it could cause issues or even damage. Your Manuals (GPU + MOBO) should cover it.

Mactronix