 The XT3 derives much of its architecture from the previous Cray T3E system, and also from the Intel ASCI Red supercomputer.The XT3 consists of between 192 and 32,768 "processing elements" (PEs), where each PE comprises a 2.4 or 2.6 GHz AMD Opteron processor with up to two cores, a custom "SeaStar" communications chip, and between 1 and 8 GB of RAM.The PowerPC 440 based SeaStar device provides a 6.4 gigabyte per second connection to the processor across HyperTransport, as well as six 8-gigabyte per second links to neighboring PEs.