The TOP500 project lists twice a year the 500 most powerful supercomputers in the world. The objective of the list is to observe trends in technology related to High Performance Computing and enlighten, ultimately, the importance of supercomputation to the development of Science and Engineering.
The MareNostrum supercomputer hosted by Barcelona Supercomputer Center occupies the position 106 in the TOP500 list this year.
The system is based on iDataPlex DX360M4 compute racks that contain Xeon E5-2670 8-core processors at 2.6 GHz. The machine has 48,896 cores with a performance peak of 1.1 Petaflops. The interconnection network is an Infiniband FDR from IBM. All of this consuming about 1MW of electrical power.
More information on the TOP500 list can be found here, such as the latest complete list.