The Tianhe-2, built by China's National University of Defence Technology in Guangzhou, can perform at 33.86 petaflop/s.
This is the equivalent of performing 33,863 trillion calculations per second and is almost double the score achieved by the second most powerful machine: the American Titan supercomputer, which clocked in at 17.59 petaflop/s.

Tianhe-2 retained its position as the world's No 1 system, according to the 42nd edition of the Biannual TOP500 list of the world's most powerful supercomputers announced on Monday.

Titan, a Cray XK7 system installed at the Department of Energy's (DOE) Oak Ridge National Laboratory, remains the No 2 system. It achieved 17.59 Pflop/s on the Linpack benchmark.
Titan is one of the most energy efficient systems on the list consuming a total of 8.21 MW and delivering 2.143 gigaflops/W.
Sequoia, an IBM BlueGene/Q system installed at DOE's Lawrence Livermore National Laboratory, is again the No 3 system. It was first delivered in 2011 and achieved 17.17 Plop/s on the Linpack benchmark.

Fujitsu's K computer installed at the RIKEN Advanced Institute for Computational Science (AICS) in Kobe, Japan, is the No 4 system with 10.51 Pflop/s on the Linpack benchmark.
Mira, a BlueGene/Q system installed at DOE's Argonne National Laboratory, is No 5 with 8.59 Plop/s on the Linpack benchmark.

The new entry in the TOP10 is at No 6 - Piz Daint, a Cray XC30 system installed at the Swiss National Supercomputing Centre (CSCS) in Lugano, Switzerland and now the most powerful system in Europe.
Piz Daint, which achieved 6.27 Pflop/s is also the most energy efficient system in the TOP10 consuming a total of 2.33 MW and delivering 2.7 Gflops/W.

Stampede at the Texas Advanced Computing Center of the University of Texas, Austin, slipped to No 7; while as a BlueGene/Q system called JUQEEN installed at the Forschungszentrum Juelich in Germany is No 8.

Number 9 is taken by Vulcan, another IBM BlueGene/Q system at Lawrence Livermore National Laboratory; and No 10 is the third system in Europe, the SuperMUC, installed at Leibniz Rechenzentrum in Germany.
The total combined performance of all 500 systems on the list is 250 Pflop/s. Half of the total performance is achieved by the top 17 systems on the list, with the other half of total performance spread among the remaining 483 systems.
The US is clearly the leading consumer of HPC systems with 265 of the 500 systems. The European share of 102 systems is still lower than the Asian share of 115 systems. Dominant countries in Asia are China with 63 systems and Japan with 28 systems. In Europe, UK, France, and Germany, are almost equal with 23, 22, and 20 respectively.