Power arrives at hundreds of kilovolts and leaves at about one volt at the chip. At every step down the voltage falls, the current climbs and resistive heat grows with its square. 800 V DC in the rack is the grid's old high-voltage trick moved indoors.

Every token that leaves a data center rides on three pipes: power coming in, heat going out, and data moving between tens of thousands of GPUs. The building can only do as much work as its narrowest pipe allows, and today that pipe is power.