No. 10: SuperMUC (IBM)
SuperMUC is a regular fixture on the Top500 list, achieving just under 2.9 petaflops on its more than 147,000 cores. Located at the Leibniz Supercomputing Center near Munich, SuperMUC is one of the less efficient entries in the latest top 10, producing just 846 megaflops of computing muscle per Watt. It's also one of five machines in the top 10 built by IBM.