The Top500 list of the world's fastest supercomputers shows IBM's Blue Gene still on top and Advanced Micro Devices Inc.'s Opteron processor now powering more systems on the list than last year. The list was released today at the International Supercomputing Conference in Dresden, Germany.

Retaining its top position on the biannual list for the fourth time, IBM's Blue Gene/L System, located at the U.S. Department of Energy's Lawrence Livermore National Laboratory, recently reached a Linpack benchmark performance of 280.6 trillion floating-point operations per second(TFLOPS). Systems closest in performance to the Blue Gene have yet to pass the 100 TFLOPS mark.

While IBM supercomputers account for roughly half of the overall list, Hewlett-Packard Co. machines occupy nearly a third.

The Top500 list, showed fewer changes than usual this year. Some 158 systems dropped off the list this time around, compared with more than 200 systems displaced in the June 2005 list.

Among other trends, while Intel Corp. microprocessors powered 301 of the systems, down from 333 last year, AMD's Opteron processor gained some ground, accounting for 81 systems, compared with just 25 a year ago.

Interestingly, most of the supercomputers on the list, that is nearly 300, are housed in the U.S. Europe now has 83 systems, which is down from the 100 systems it had six months ago. Asia's share is now at 93 systems, up from 66 six months ago.