NVIDIA is working on a fix to allow the HTC Vive to be connected to the GeForce GTX 1070 and GTX 1080 over DisplayPort. The HTC Vive apparently has the choice between HDMI and Mini DisplayPort, but the headset will not be identified when connected over that connection. Currently, the two workarounds are to connect the HTC Vive over HDMI, or use a DisplayPort to HDMI adapter if your card's HDMI output is already occupied.
It has apparently been an open issue for over a month now. That said, NVIDIA's Manuel Guzman has acknowledged the issue. Other threads claim that there are other displays that have a similar issue, and, within the last 24 hours, some users have experienced luck with modifying their motherboard's settings. I'd expect that it's something the can fix in an upcoming driver, though. For now, I guess plan your monitor outputs accordingly if you were planning on getting the HTC Vive.