8K displays were everywhere at CES this year, which means HDMI 2.1 had to be there to actually drive them. HDMI 2.1 basically existed as a standard and little more in 2018, but the Japanese site 4Gamer took a particularly hard look at the state of HDMI 2.1 at the trade show. Apparently, the chips used to transmit and receive HDMI 2.1 signals are just now going into production. Some 8K TVs will get 2.1 support right off the bat, while others will enable it later through a firmware update. But 4Gamer noted one particular limitation that could hinder the adoption of the display standard: cables over 3 meters (which is just under 10 feet) will have to be active, powered cables. Additionally, cables over 5 meters will have to be active optical cables. While such cables usually draw the power they need from the HDMI port itself, 4Gamer notes that active cables are significantly more expensive than "dumb" copper ones. And unlike passive cables, active HDMI cables are directional, meaning users will have to plug the correct ends into the source and the display if they want to get a signal through.