Data centers are facing serious energy challenges. Increasing energy costs make the operation and cooling of servers more significant cost factors. Furthermore, improvements in technology have led to processor chips and systems with rapidly increasing power density. The resulting power consumption and cooling requirements of these systems are pushing many existing data centers to the limits of their power distribution capability and cooling capacity. Improvements in energy efficiency and management are needed at the chip and the system level to counteract this trend. This paper provides a comprehensive description of the hardware and firmware improvements implemented with IBM zEnterprise® 196 to stop the growth of and even reduce its energy footprint compared with previous IBM System z® servers. These include more power-efficient chips; power conversion and distribution; new sensors; cooling control firmware; new energy management functions; integrated hybrid energy management for power saving and power capping across the whole hybrid system; and data center energy-efficiency improvements resulting from options for water cooling, high-voltage DC (HVDC) power, and overhead cabling.