Video Card = 2pin SPDIF, Motherboard = 3pin SPDIF: What do?

Spdif should just be 2 wire (signal and ground). Are you sure that motherboard header is an input? I have one on my asus boards but I think they are output.

Since it is just spdif, why not use the spdif from the mb onboard sound?

Needs to be connected to pins 2(spdif out) & 3(ground) according to the manual. Pin 1 is vcc which is used for optical, NOT COAXIAL.

You need something like this because the 4 pin header that came with your video card won't fit onto the motherboard 3 pin spdif output.
http://www.logicsupply.com/products/cabhdr254_20


EDIT: Just noticed the asus supplied cable has a Y split to a 2 pin header. You can use this, just make sure its connected properly. Black should be ground and the blue cable is spdif.

The four pin connector is only using 2 wires. If pins 2&3 are the ones needed to be connected, just let it overhang the motherboard. You can always change the position of the wires if you have to. Just make sure the ground is the same color wire on the motherboard and the video card. If the 4 pin connector won't work, take a small punch and depress the locking tab of each wire and remove the 2 wires from it and hook up that way, or cut the 2 empty slots off of the connector. You don't need any kind of adapter to make this work. Don't worry about other pins they aren't used.

The 3 pin header on the motherboard looks like this


which is why the 4 pin wont fit.

Just remove the wires or trim the connector to fit.

Pair of cutters will work for trimming the spdif cable.

Unfortunately, while most connectors on motherboards (eg. USB, Firewire, Serial/Parallel ports, FP audio) are standardized, SPDIF headers are not.
All manufacturers follow their own spec. So Asus boards have a 4 pin header, a few have the 3 pin headers (like you described) and Gigabyte has a 5 pin header for In & Out. (Very few manufacturers have SPDIF IN).

What are you connecting this to? TV? AVR?
And what kind of files are you playing?

Is there any setting in your TV menu to change from analog audio to digital for HDMI input?

Trimming of the header was not necessary. The white header connects to the video card and the 2 pin connects to the motherboard( Pins 2 & 3). The 4 pin connects to nothing.

Your right Mrkazador. Didn't look close enough at the cable picture this morning.

Really? That is weird...

Did you make spdif the default audio device in windows?
Control Panel- Sounds: Select SPDIF and set to default.

Hi,

It has been a while since the last post but I will send my solution regardless as it might still help somebody with this issue.

I have an ASUS 9800GT graphics and an ASUS P45 motherboard, the former with a 2-pin connector, and the latter with a 3-pin one. The cable provided with the graphics was exactly the same as on brittnell's picture at the beginning of this thread.

So I had the same problem as he had - no audio via HDMI. After reading through several forums on the web with no useful answer to this and being at wits' end I decided to experiment a bit.

Since the cable has only 2 wires, only 2 pins have to be connected on either end.
The 4-pin cable connector could not fit in the motherboard so I used the 2-pin one, sticking the black wire to the the ground pin and the blue wire to the signal pin.
This had left me with the 4-pin connector for the graphics card. The signal pin was marked with an arrow so I connected it to the blue wire and the other pin to the black one.

It worked.

One more thing:
Before you start playing with your own hardware make sure you check the motherboard's documentation on the exact pin arrangement. And make sure that it is the SPDIF-OUT connector, not SPDIF-IN as there was some confusion about it earlier in the thread. The same goes for the the graphics card - checkits manual to be sure about the pins' functions.

Cheers,
Lukas