7M or 25 ft HDMI cable for 4K UHD

I use a 35' Blue Jeans BJC HDMI cable to run from my Oppo UHD player to a 4K projector. Works perfectly on streamed and BD 4K video content. I can't comment on audio quality as I only run video on the HDMI cable.

This is exactly what I'll be doing...No audio, just video 

I also run 25' Blue Jeans HDMI cable from my Oppo 205 a 4K projector and have never had any problems. I only run video on the HDMI also.

Grab a cable with a lower wire gauge, they are best for longer runs. Blue Jeans has the BJC Series 1 (23.5 gauge), Sewell Direct has a 22 gauge hdmi cable that I found to be a little better (can't remember the pricing, but they were close to the same). I think the minimum length for the Sewell was 8 feet or so, the thing was like a garden hose (when I sold mine the post office clerk literally asked if I was shipping a hose).

Both cables are thick and heavy, so be prepared to have or create some sort of suspension rig if you are plugging the cable into the tv sideways (some tv's have vertical plugs under the tv which works better for these cables). I just wrapped a piece of Gorilla Tape around part of the cable and attached it to the back of the tv then put another piece across that one horizontally. There are actual brackets that one can install though if need be.