Hi gang, Have a small dilemma here. My video card has 1 HDMI port and a couple display ports and a DVI port I think. My 1080p monitor is connected to DVI. And my Oculus Rift goes into the HDMI port and then my 4K tv goes to a HDMI to display port adapter. My dilemma is I can't find a way to get Oculus working AND a 4K on my TV simultaneously. If I have my Oculus in the HDMI and my 4K tv going to the display port adapter I can only get 1080p resolution. And that's even using an HDMI 2.0 4K cable. If I swap the cables, and have the 4K tv going into the HDMI port on the video card I get 4K fine. But then the Oculus Rift won't at all going through the display port adapter. I don't know if there's a way to get both working but right now I'm having to swap ports back and forth for whichever device I want to use. Very annoying.
So you want to duplicate the image between Oculus and TV, right? I seriously doubt Oculus can run 4k, that's why you're limited to 1080p duplicate. Duplicate displays can't have different resolutions. You can select the main display in nvidia control panel though, no need to switch cables around. Set Oculus as main when using it and TV as main when you need 4k.
I have no experience with occulus rift, sorry. though, you may not know this most HDMI monitors will cap you at 30Hz if you try to run 4K. make sure you research your brand first. if you are trying to force 60Hz that could be why it is reverting to 1080P. and there is no such thing as an HDMI 2.0 cable. what you have is a "high Speed" HDMI cable. and you may need TWO high speed cables if you connect it to something in the middle. you cannot mix a regular cable and a high speed cable and expect "high speeds". for instance, game box to stereo receiver to HDTV.