China is routing the US when it comes to building supercomputers, something which is a little surprising given that most of the technology should be in the US. China retook the top spot in the 41st Top500 listing of the world's most powerful supercomputers with its Tianhe-2. The computer could manage 33.86 petaflops, or 33.86 thousand trillion floating point operations per second.

This is more than twice as many petaflops as the second computer on the list, Titan, a Cray XK7 system installed at the US Department of Energy's (DOE) Oak Ridge National Laboratory. The top system in the previous Top500 competition, compiled in November, Titan clocked 17.59 petaflops on the Linpack benchmark for this round of the Top500.

What appears to have surprised the pundits is that the Chinese got the system going two years early, which is why it is light years ahead of the US. China's National University of Defense Technology built Tianhe-2, or Milky Way-2, with 16,000 nodes. Each node runs two Intel Xeon IvyBridge processors and three Xeon Phi processors, for a combined total of 3.12 million computing cores.

It is located at the National Supercomputer Center in Guangzho, China.