The IBM chips show up in a $5.2 million system officially named X but informally dubbed "Big Mac that Virginia Polytechnic Institute and State University researchers assembled over two months from 1,100 dual-processor Apple G5 computers. That system ranked No. 3 with a performance of 10.3 trillion calculations per second, or 10.3 teraflops.
The Opterons are used in a 2,816-processor cluster built by Linux Networx for Los Alamos National Laboratory. Its sustained speed is 8 teraflops.