PowerPC performance about more than clock speeds

Choosing the highest-performance computer based on the latest PowerPC processors from IBM and Motorola isn't as easy as selecting the one with the highest clock speed, according to Microprocessor Report. Earlier this month, the PowerPC team boosted the performance of the 604e to 350 MHz, the fastest PowerPC CPU yet - and about 20% faster than a 300-MHz Pentium II in either integer or floating-point operations. But for 'real-world' applications the PowerPC 750 chip is better yet, despite its 266MHz clock speed.

Choosing the highest-performance computer based on the latest PowerPC processors from IBM and Motorola isn't as easy as selecting the one with the highest clock speed, according to Microprocessor Report.

Earlier this month, the PowerPC team boosted the performance of the 604e to 350 MHz, the fastest PowerPC CPU yet. The PowerPC duo also offers the PowerPC 750 processor at a slower 266 MHz, but it has a second bus that, like the dual-independent bus of Intel's P6, allows higher-speed access to Level 2 cache, explains Linley Gwennap, publisher and editor in chief of Microprocessor Report.

As a result, the two CPUs produce better results on different tests, Gwennap says.

The 604e is about 20% faster than a 300-MHz Pentium II in either integer or floating-point operations, Gwennap notes.

"We're going to be able to do things that flat-out can't be done on the Intel architecture," said Will Swearingen, manager of PowerPC product marketing for Motorola.

However, it is the 750 that shines in real-world applications, Gwennap said.

The 750 "was optimized for Macintosh," Gwennap says. "The difference is the extra bandwidth of the 750's backside cache bus."

"We've spent time looking at Mac code in order to optimize it for the Mac platform," says Lori Peterson, manager of PowerPC product marketing for IBM Microelectronics.

The Somerset Design Center of the Apple-IBM-Motorola alliance, in Austin, Texas, can be reached at http://www.ibm.com/ or http://www.motorola.com/.

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