The world’s most energy-efficient systems for the second time running were three QPACE systems based on the IBM PowerXCell 8i processor, all in Germany, Green 500 organizers announced last week. 

 

The three – at the Julich Supercomputing Center, University of Regensburg and University of Wuppertalare - tied for the top spot on the list, which is created every six months.

 

The rankings gauge the energy efficiency of supercomputers by measuring millions of floating-point operations per second per watt, or Mflops/W. The IBM systems each produce more than 773 Mflops/W, Green 500 said.

 

The list was also dominated by accelerator-based supercomputers, which took out the top eight positions.

 

Green500 co-founder Wu Feng, associate professor of computer science and electrical & computer engineering at the Virginia Tech College of Engineering said: “The accelerator-based supercomputers on The Green500 List produce an average efficiency of 554 MFLOPS/W, whereas the other measured supercomputers on the list produce an average efficiency of 181 MFLOPS/W.

 

“That makes the accelerator-based supercomputers on the Green500 more than three times more energy efficient than their non-accelerated counterparts,” he said.

 

The accelerator-based supercomputers come in two flavors: one is based on the custom PowerXCell 8i processor from IBM; and the second is based on graphics processing units (GPU) from AMD or NVIDIA.

 

Feng said Chinese-made high-performance computers had used the GPU as an accelerator.