Blue Gene/L, a supercomputer developed by

IBM

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and the U.S. Department of Energy, has clinched the title as the world's fastest, beating out a previously top-ranked computer from Japan's

NEC

.

According to the latest ranking of the world's top 500 supercomputers, which is issued twice each year, NEC's Earth Simulator tumbled to third place after claiming the lead position for 2 1/2 years. Moving into second place was a supercomputer from

Silicon Graphics

(SGI)

.

The Top500 list of supercomputers is compiled by computer experts at the University of Mannheim in Germany, Lawrence Berkeley National Laboratory and the University of Tennessee.

Computer experts say the

rankings don't usually have much bearing on sales of lower-end fare for business customers. But in an added twist on Monday, IBM unveiled a scaled-down commercial version of Blue Gene based on its proprietary Power microprocessors.

A 1-meter-size version of the system, available starting at $1.5 million, offers peak performance of 5.7 teraflops (trillions of floating point operations per second), compared with the nearly 71 teraflops of the full-fledged Blue Gene supercomputer that now leads the global rankings.

IBM currently claims 43% of systems in the top 500, with 49% of installed performance, compared with

Hewlett-Packard's

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35% of systems and 21% of performance.

IBM closed up 27 cents, or 0.3%, to $93.37; H-P was up 12 cents, or 0.6%, to $19.81; and Silicon Graphics gained 2 cents, or 1.6%, to $1.28.