PSU pin.

[CrossLOPER]

Does it look like any of these?

No. I passed that site while I was looking for answers. I only just now realized how awesome it is. Thanks.

It could be something like a connection for a PSU fan speed sensor or something equally useless.

Edit: If you can connect a suitable power lead from the PSU to your mobbo and you have successfully booted up, my guess it you don't need to worry about it.

You may be right about it being for a sensor! The GTX260 has a similar port and I would imagine someone with a ricer case making use of it. I would just boot it up, but I don't want to risk damage to the computer.