How too connect my spdif in mobo to graphic card

Well I want to use the computer to view movies on my tv through hdmi cable, as it supports sound aswell I would like to connect the digital sound to my graphic card.
As said I have a motherboard with spdif out pins, something like
http://www.3dnews.ru/_imgdata/img/2007/08/19/56782.jpg
(in the left side of the image)
But I have goten a 2 pin connector to my graphic card, its a NX8500GT
http://www.msicomputer.com/support/formviewer.asp?esoformid=2722
,like the top one in the page
But I have no idea how to connect it, as you can see in the first pic there are 3 pins
The motherboard I have is:
http://www.foxconnchannel.com/product/Motherboards/detail_overview.aspx?ID=en-us0000243#

So any idea, how I can connect them togheter, motherboard and graphic card?