Cray's massive Titan system is now the world's fastest supercomputer, knocking off IBM's Sequoia after only six months in the top position.

The Top500 list of the fastest supercomputers was released Nov. 12 at the SC12 supercomputing show in Salt Lake City, and Titan—a Cray XK7 system installed at the Oak Ridge National Laboratory in Tennessee—took the No. 1 spot with a performance of 17.59 petaflop/s, or quadrillions of calculations per second. The system boasts 560,640 processors, including 261,632 of Nvidia's Tesla K20x GPU accelerators, which also were announced at the show Nov. 12. It runs Advanced Micro Device's Opteron 6274 processors.