PNNL: “The PNNL system is the worlds fastest supercomputer based on the Linux operating system and is the largest machine ever built using Intels 64-bit architecture.
PNNLs supercomputer draws its speed and computing power from nearly 2,000 next-generation Intel® Itanium®-2 processors code-named Madison, running on industry-standard HP Integrity servers. Linking the Intel Itanium2 chips is a Quadrics interconnect that provides communication between processors and allows scientists to sustain a high performance level. HP is providing services to customers that help manage, deploy and enhance the power and ability of supercomputing.”
Gimme gimme! ;)