oled55cx3la

I know this question already was created but I did not find a solution. I have a video card ASUS Radeon 390x. I connected a 4K TV LG OLED55CX3LA on DisplayPort->HDMI with high speed cable "Goobay 71962" . The max frequency in resolution 4096x2160 is 30Hz. The operation system is Windows 7. All...