55X8005C (X80C) - 4k@60hz, 1080p@120hz and HDR questions

[Bilazaurus]

Hi,

I have bought 55X8005C which is X80C series. I have several questions to which I cannot find solid answers

1. I cannot display 4k resolution at 60hz with my PC. It just says "no signal" but it displays 4k@30hz. What is the max HDMI cable lenght to provide enough bandwidth? I have a 5 meter HDMI cable rated, presumably, HDMI 2.0. Is the cable poor quality or what? I have a top-end graphic card - GTX980Ti so I don't think GPU is the problem.

2. Can X80C display 1080p in 120hz? I want to play older games at 1080p with 120fps running from my PC. Is 120hz REAL in this TV? Is it possible to achieve real 120FPS?

3. I've seen that X810C which is USA version of X8005C received an firmware update introducing HDR but I cannot see that in European firmware changelog. Will X8005C get HDR?

[Bilazaurus]

I've done everything above some time ago

Blurbuster always shown "Fine". FRAPS shown 119FPS.

I tried everything because 120hz advantages were not visible at all.

You wrote that you got it working...

BUT

Did you read that little line about taking photos of your TV while doing a frame skipping test?

Go ahead. Take a picture of your TV your mobile phone while doing frame skipping test. You'll see what I'm talking about.