The hyperspeed growth of data center power demand starts with the high power consumption required by the current and upcoming generations of digital application-specific integrated circuits (ASICs)-central processing unit (CPU), double data rate memories (DDR) and networking ASICs-in addition to the exploding use of high-power graphics processing units (GPUs) for artificial intelligence and machine-learning functions. Hyperscale data centers will also increase in number, from 259 at the end of 2015 to 485 by 2020. They will represent 47% of all installed data center servers by 2020 [1]. Server shipment growth has been driven by large, hyperscale data centers, where servers are often configured for maximum productivity and operate at high utilization rates. Server power consumption is perpetually escalating, and this trend will continue into the near future for both midrange and high-end power servers [2], as shown in Figure 1.