[goodton]

@Usafle : Your video test is a fine example of this Windows 7 -limitation for 10-bit HEVC-playing. The left one is Main10-file, which is not supported from HW-decoding standpoint in Win7, that's why it will be SW-decoded and will choke your CPU. The right one will be HW-decoded an will run easily with your setup as being Main-level file supporting max. 8-bit 4:2:0. In Windows 8 and above both examples will be HW-decoded.

What is strange, that in your case the Adjust Refresh Rate To Match does not work as this a very critical setting for judder-free playing for files with different FPS. By the way, from resourcing point of view the True Fullscreen is better than Windowed Fullscreen, which I think is the default setting in Kodi. I would also test that setting in your case.

EDIT: Might sound strange but even the latest HDMI-2.0b -spec, which your GTX 1050 also supports, has a bandwidth limit = 18Gbps. In practice combination of 4K-resolution, 60 Hz, full RGB or 4:4:4 and 10-bit output is not possible. So a compromise is needed. You have couple of options, use 8-bit output or use those compressed 4:2:2- or 4:2:0-formats with 10-bit. In theory you could also drop your desktop FPS to somewhere 48 Hz or below to decrease the bandwidth needed.