You can't always believe everything you read on a computer box. Even clock speed-that gigahertz-expressed metric most computer buyers associate with a machine's power-may not mean what it used to. A spat between computer titans Sun Microsystems and IBM over just how misleading the measure is has led to a fledgling industry effort to find a more accurate way to gauge a computer's abilities.

The problem is a result of new trends in chip design. Clock speed refers to the frequency with which a chip's central processor does basic operations. Specialized new chips have multiple processors that can end up competing for access to memory, creating bottlenecks that may worsen with future multiprocessor chips, says David Yen, Sun's executive vice president of processor and network products. But while they may perform at a slower clock speed than today's chips, the multiprocessor chips Sun plans to build will run many software programs faster because the additional processors let the chips handle more incoming and outgoing data. Clock speed, Yen asserts, is often "used in a misleading way and overhyped. We're looking for a more appropriate yardstick."