is now #3 on the Top 500 supercomputer
list. It resides at the Lawrence Livermore National Laboratory
where it simulates nuclear
reactions. It can perform 12.3 TFLOPS
peak/7.3 TFLOPS max; the NEC Earth Simulator
handily trounces it, but keep in mind this was state-of-the-art at one time.
ASCI White is composed of 8192 Power3 processors (512 16-processor RS/6000s), weighs 106 tons, and cost $110 million to build. It runs a parallelized version of AIX. This is not your father's supercomputer.
Information gleaned from http://www.top500.org/ and http://www.llnl.gov/asci/platforms/white/