Energy-Efficient Computing and Data Centers

2Cooling Servers

2.1. Evolution of cooling for mainframe, midrange and distributed computers from the 1960s to 1990s

The first general purpose digital computer was built by IBM in 1944. This electromechanical device codeveloped with Harvard was the pioneer in computing. Following in 1948, the electronic calculator SSEC, which contained about 21,400 relays and 12,500 vacuum tubes, was at the origin of power consumption criticality considerations and able to deliver compute performance of thousands of calculations a second. The large mainframe computer from 1944, the ENIAC, consisted of 30 separate units, plus power supply and forced-air cooling, and weighed over 30 tons. Its 19,000 vacuum tubes, 1,500 relays and hundreds of thousands of resistors, capacitors and inductors consumed almost 200 kW of electrical power.

By the mid-1950s, transistors had begun to replace vacuum tubes in computers to improve reliability, performance and power consumption and in 1958, IBM announced the 7070 Data Processing System using transistors that incorporated solid-state technology. A big leap was eventually made in the mid-1960s with the introduction of the IBM S/360 that lead to dominance of mainframe computing for a few decades. The processing unit of the IBM S/360 model 85 (IBM Systems Reference Library 1974) was composed of 13 frames with a total footprint of 15 m² a power consumption of 9.3 kW and with a clock frequency of 12.5 MHz. In addition to the power consumption, the mainframes needed ...