User Manual LG OLED77C9AUB C9 77 inch Class 4K Smart OLED TV

You will be able to get 4K @ 60Hz and 8K @ 30Hz with current cables when connected to the HDMI 2.1 ports on the LG C9 65 inch Class 4K Smart OLED TV w/ AI ThinQ® (64.5'' Diag), Model # OLED65C9PUA, but for increased resolutions and higher frame rates, you will need an Ultra High-Speed HDMI Cable. Most current HDMI cables can handle nearly all of today's content. HDMI 2.1 is predominantly for people who will want to send their 4K TVs native 120 fps or 8k TVs 60 FPS material. Personal computers and high-end gaming rigs are the only current sources that can output 4K at more than 60fps. The Xbox One X can do 120fps, but only at lower resolutions and therefore doesn't require HDMI 2.1. Other than gaming, there's basically no current content that requires the bandwidth of HDMI 2.1..

It is not that the LG C9 55 inch Class 4K Smart OLED TV w/ AI ThinQ® (54.6'' Diag), Model # OLED55C9PUA or any other TV for that matter, cannot be mounted above a fireplace. The practice of mounting a TV over a fireplace has somehow become extremely popular in the U.S. What you need to consider before making the decision to mount it above a fireplace is Electronics don’t care for heat, and they care for smoke even less. Particulate from the fire can build up and cover the components inside the TV causing the heat generated by the TV to build up. The TV has an optimal operating temperature of between 0 °C to 40 °C (32 °F to 104 °F). Beyond that, excessive heat can cause temperature-sensitive materials to degrade quickly, and conductive materials can even sprout little metal whiskers, causing shorts within the TVs circuitry. If you're not using the fireplace, then that not an issue. The other thing you need to consider is how high above the ideal level the TV will be installed above your fireplace. Placing it above a fireplace moves the image you’re trying to watch well above eye level. That could put you in an uncomfortable position where you're having to crane your neck which could result in headaches or neck aches due to poor posture. You can always get a mount that allows you to angle the TV down towards your viewing angle to accommodate for this. So it is not that you can't mount the TV over a fireplace, you just have to consider a few things before making the decision

Yes, all the HDMI ports on the LG Electronics OLED55C9PUA C9 Series 55" 4K Ultra HD Smart OLED TV (2019) are full spec HDMI 2.1 ports.