Most Expensive Supercomputer in the US

IBM’s BlueGene/L machine is both the fastest and most expensive supercomputer ever built in the United States. It was built at the US Department of Energy’s Lawrence Livermore National Laboratory in California. The supercomputer is built from 64 racks of Blue Gene servers, each of which contains 1,024 700MHz dual-core PowerPC processors.
Specifications listed on LLNL’s website about their BlueGene/L system
are as follows:
65,536 compute nodes, each targeted for 2.8 GFlop/s peak
Chip multiprocessor with 4MB L3 cache on chip
High-bandwidth low-latency 3D torus and combining tree networks
32 terabytes of memory
High-performance kernel on compute nodes, Linux on I/O nodes
Hardware support for Message Passing Interface collectives
BlueGene/L currently tops the TOP500 Supercomputer Sites list with a Linpack performance benchmark of 280.6 TFlop/s.
IBM sells a single 1,024 processor BlueGene rack for approximately $2,000,000. The BlueGene/L supercomputer was built by IBM for the DoE along with the ASCI Purple supercomputer that benchmarks at 63.39 TFlop/s as part of a $290,000,000 contract. The supercomputers will both be used for nuclear weapons simulations.