A few months ago, Virginia Tech completed the assembly of their new G5 Xserve based supercomputer, using 2.3 GHz Xserves which are unavailable to the general public.
Virginia Tech has now submitted its new Linpack benchmark scores to the interim Top 500 list:
IBM now leads the list with its BlueGene cluster of 16384 0.7 GHz PowerPC 440 CPUs. Japan's Earth Simulator, long in the lead, now is in second place. It appears that third and fourth place on this interim list are the same Itanium 2 based machine just with different amounts of CPUs. If this is the case, the lower score will be removed for the final list, and fourth place would thus belong to ASCI Q. Another BlueGene cluster (with a smaller number of CPUs, at lower clock speed) gets fifth place.
In sixth place is Virginia Tech's Xserve G5 cluster, and the list confirms its use of 2.3 GHz G5s. The system also uses less CPUs than the previous system, at 2048 2.3 GHz CPUs compared to the previous 2200 2.0 GHz G5s. Despite the fewer CPUs, the new system has a higher theoretical peak score, and with it VT has managed to hit 10930 Gflops/s (58.0% efficiency vs. peak), just edging past their previous score of 10280 (58.4% vs. peak), which ranked third at the time. If VT adds more nodes to its current Xserve system, or tweaks their bench a bit more, it is possible they could reach 11000 Gflops/s or higher. However, VT would need a 7% boost in overall speed to move up one place into the top five, since BlueGene DD1 is already at 11680 Gflops/s.
It is also interesting to note that as it stands currently, the three of the top six are PowerPC based systems, including 2 BlueGene clusters, and VT's G5 system. The other three systems include one (Earth Simulator) that uses custom chips from NEC, one that uses Alpha chips, and one that uses Intel's Itanium 2 chips.