NorthEndJon They have had Digital Audio Passthroughs on nearly every card I've ever seen from Nvidia. I know the GTX480 has one. Its so you can use your sound cards digital out with your HDMI connection to your TV.

cadaveca I do not beleive that the 5-series cards had this audio port. As soon as you mentioned the audio port, I thought "heck, yeah, that's what it is...", and then Iremembered the 5-series cards...



590(with similar secondary fan port):



www.techpowerup.com/reviews/ASUS/GeForce_GTX_590/images/front.jpg



580:



www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_580/images/front.jpg



570:



www.techpowerup.com/reviews/ASUS/GeForce_GTX_570/images/front.jpg

They haven't need the digital pass though since the GTX200 series. The 400 and 500 series all have a built in audio processor that outputs sound via HDMI so no sound input to the card is requried. The GTX480 definitely does not have an audio passthrough.I don't think it is a audio port. I think nVidia is done with requiring that now that they have a working sound card design that they can include with the GPU. As you pointed out, the GTX590 has a similar connector that isn't an audio connector. I'm guessing it is something else, possible a place to connect an LED or something for a light in the heatsink.Edit: I just went back and looked at the GTX590, the port is definitely used to power the little LED to light up the GeForce logo. So I'm certain that is what is is being used for here as well.