The power is only needed for transcoding. Multiple 4k streams should be little more than directly serving up the files to the client machine (like your TV) which consumes very few resources. You should avoid transcoding 4k down to 1080p or 720p by either avoiding 4k content, grabbing only stuff that is directly compatible, or having duplicate copies of stuff in 4k and 1080p so that the 1080p file gets transcoded if needed. Many of us have separate 4k libraries on our servers to prevent any possibility of transcoding it (like for remote streams when you don’t have the upload speed to stream 4k directly).