从 345 kV 的高压线降到芯片上的 1 V，电压一路降，电流一路涨，发热跟着电流的平方涨。800 V 直流进机柜，其实就是把输电网高压低流的老办法搬进机房。

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.