K is built by the Japanese computer firm Fujitsu, based in Kobe's Riken Advanced Institute for Computational Science. It is capable of making 8.2 quadrillion (a quadrillion is 1 followed by 15 zeroes) calculations per second - or, in computer jargon, 8.2 petaflops.
The previous fastest machine was the Chinese computer Tianhe-1A, which was clocked at 2.507 petaflops.
The rankings for the world's fastest computers are kept by a professor of electrical engineering and computer science at the University of Tennessee at Knoxville, one Jack Dongarra. He releases a six-monthly list detailing the top 500 machines, as determined by a their ability to run a standard mathematical equation. The new list is released today.
K's performance is equivalent to one million linked desktop computers, according to Prof Dongarra, or more than its five closest competitors combined. It consists of 672 cabinets stuffed with circuit-boards, and its creators plan to increase that to 800 in the coming months. It uses enough energy to power nearly 10,000 homes and costs $10 million (£6.2 million) annually to run.
“It’s a very impressive machine,” Prof Dongarra said. “It’s a lot more powerful than the other computers.”