The megahertz myth

Apple's recent move to lower the speeds of its new Power Mac G4 line by 50MHz across the board had a couple of unintended consequences.

First, the "reconfiguration" -- which was intended to compensate for unexpected "errata" in Motorola Inc.'s processors that prevented the current crop from reaching the advertised top speed of 500MHz -- kicked up a controversy among users whose orders Apple seemed poised to cancel.

That issue, at least, has largely been resolved; the company wisely decided to honor existing pre-orders at the original speeds and prices. (That applies to the 400MHz and 450MHz flavors of the processor, of course; the contentious 500MHz version has apparently been pushed back to early 2000.)

As I've argued before, the more enduring problem is the extent to which the downtick focused undue attention on raw megaherz, an arena where the PowerPC undeniably lags behind its platform counterparts.

There's no arguing with the numbers: While the shipping G4 currently tops out at 450MHz, Intel's first crop of Coppermine Pentium IIIs for desktop systems debuted at a maximum of 733MHz, even beating out AMD's freshly minted 700MHz Athlon processor.

Even if I concede this point, it doesn't mean I'm prepared to endorse megahertz as the cornerstone of performance. Even if Moto had been able to deliver the 500MHz G4 this go round, the first-generation Power Mac G4's strongest selling point still wouldn't have been pure processor speed.

Thankfully, there's a whole lot else to recommend these systems performance-wise: According to the much-hyped "gigaflops" yardstick, the Power Mac G4 couples enviable floating-point performance with low power output. The 100MHz system bus puts the systems' throughput on a par with most current PCs, especially since technological problems have plagued Wintel boxes' promised 133MHz bus. And the G4's Velocity Engine extensions offer a whole new dimension of multimedia performance that soundly beats the Pentium III's SSE efforts.

Furthermore, the playing field levels off even more when it comes to portable computing. While the mobile version of the Coppermine chip -- the first Pentium III that could even get near a portable without frying it -- tops out at 500MHz, for example; meanwhile MacWEEK sources agree that the full-strength G4 already runs cool enough to fit into a laptop. In fact, Apple is reportedly working on 400MHz and 450MHz G4 PowerBooks that may see the light of day as early as January's Macworld Expo in San Francisco.

Furthermore, help is on the way, both from Motorola and IBM Corp., the third partner (along with Apple and Motorola) in the PowerPC troika. According to MacWEEK's sources, the current roadblock on the G4 is one of fabrication, not design; to underscore the point, sources report that a 720MHz G4 is already running just fine, thanks, in Motorola's Austin, Texas, Somerset design center.

Furthermore, IBM's focus on pumping up the speeds of the PowerPC architecture -- hitherto focused on the server market -- should serve the Mac in good stead now that the company has joined the desktop G4 push. As one observer told me, "IBM could've gotten the 500MHz G4s out months ago."

This speed push should make great propaganda tools to quiet PC proponents obsessed with this spec. However, at the end of the day, it's performance that counts, and the Power Mac G4 already gives the lie to the megahertz myth.

Matthew Rothenberg is director of online content for Mac Publishing LLC, which publishes MacWEEK, MacCentral, Macworld and MacBuy.