Five of the world's top 500 supercomputers are based on Apple Xserve systems, reveals the twenty-seventh iteration of the Top500 list of the world’s fastest supercomputers.

Each of the five Apple-based systems have fallen slightly in the ranking.

In twenty-first place is Colsa’s Mach 5, down from 15th position in last November’s list. Virginia Tech's System X, is now in 28th place, down from 20th six months ago, and 14th position last June.

The University of Illinois' Turing system is in 114th place (from 85), the University of California’s Dawson features in position 462 (down from 303) and Bowie State University’s Xseed is ranked 468 (304).

A total of 301 systems are now using Intel processors. The second most commonly used processors are the IBM Power processors (84 systems), just ahead of AMD Opteron processors (81).

The number one position was once again claimed by the BlueGene/L System, a joint development of IBM and DOE’s National Nuclear Security Administration. It has held the number one position for the last three Top500 lists.

The UK now has the most supercomputers in Europe: 35 in total. The list is updated every six months.