IBM delivered its first "Aquasar supercomputer," which's cooled by water, to a Swiss technology institute. The system needs 40% less energy to run than air-cooled machines, and the waste heat it produces can be used to warm buildings. "The system works thanks to micro-channel liquid coolers attached directly to processors, one of the biggest culprits of computer heat generation. IBM says water is 4,000 times more efficient at removing heat than air. In the past, water was commonly used to cool mainframes and other large computing systems, but typically that water was kept at low temperatures."