"Dell specifies[1] 87W (typical) to 125W (max), with 89.5W in Energy Star mode. Has anyone ballpark-estimated power requirement to generate the video signals driving such a monitor?"

I've never looked at LCD panel power usage before ... are those numbers high or low or ... ?

If I go to best buy and buy a 50" samsung 4k TV, what would that power usage be, roughly ?

(just trying to get a sense of comparison)