If you have a Pascal GeForce graphics card and an HTC Vive, it seems that trying to run the VR headset using the DisplayPort input on its included breakout box doesn't work right now. If a Vive is set up this way, the SteamVR software fails to detect the headset and presents users with an error message. Tom's Hardware broke the story yesterday after a Tom's editor's friend couldn't get his Vive working using a GTX 1080 and the card's DisplayPort output. We've confirmed this behavior with the HTC Vive and GTX 1080s in the TR labs, and it's worth noting that the issue has been circulating on the Steam forums for some time.
Nvidia's Manuel Guzman posted the following statement on the GeForce forums regarding the issue:
We are aware of user reports of an incompatibility when plugging HTC Vive into GeForce GTX 1080 using the DisplayPort connector. HTC and NVIDIA are investigating the issue. In the interim, we recommend users connect HTC Vive to the HDMI port on GeForce GTX 1080.
To be fair, running a Vive over DisplayPort seems like an uncommon configuration to us. It requires going out and purchasing a DisplayPort-to-Mini-DisplayPort cable, since HTC doesn't include one with the Vive. Still, users who want to run a Vive and another HDMI device (like a monitor or TV) all at once are rightfully honked. Perhaps Asus got lucky when it equipped its GeForce GTX 1070s and GTX 1080s with multiple HDMI ports instead of the three-DisplayPort, one-HDMI setup common on other Pascal cards.