Under the Hood
Under the Hood Even though the Mac community is less megahertz-obsessed than are its PC counterparts, the average Apple watcher could be excused for expecting a bigger jump in processor performance. Ive certainly heard reports for months of prototype systems running at 1.4 to 1.6GHz, but apparently Moto simply wasnt able to produce these peppier chips in sufficient quantities to slake Apples thirst.The relatively puny delta between the speeds of Januarys models and Augusts undoubtedly colored Apples decision to roll out these new towers without benefit of a Steve Jobs-orchestrated media event or other marketing bells and whistles afforded, say, the flat-panel iMac. (Thanks a lot, Motorola!)Thats a shame, since theres a lot to like about the new Power Macs, including new architectural features derived from the same wellspring of innovation as the Xserve, Apples new rack-mounted server. For starters, the whole professional line is now dual-processor. Apple toyed with doubling up chips as far back as the Spindler administration, but the effort dwindled because of limitations in some earlier flavors of the PowerPCand especially in the classic Mac OS. For professional users who are ready to make the leap to Mac OS X (a population still gated by the lack of Carbonized versions of QuarkXPress and some pro-multimedia applications), the Unix-based OS support for symmetrical multiprocessing should give these systems a serious goose compared with single-processor Wintel boxes at higher clock speeds. Other niceties promise to propel these new systems comfortably ahead of the 25 percent speed boost: Xserve-derived support for DDR-RAM; an ATA/100 bus for storage, compared with ATA/66 for its predecessors; 2MB of L3 cache on the 1- and 1.25GHz models; and an ATI Radeon 9000 Pro video card on those two machines. The system bus has risen to 167MHz system bus from 133MHz in earlier models. While I expect a bigger boost in future Macs, Apples Greg Joswiak does argue that the new systems feature multiple independent buses a la the Xserve, which should wring some more performance out of the hardware. Perhaps not surprisingly, the hairiest fly in this soothing Apple ointment apparently bears a Motorola logo: According to XLR8YourMac and other independent observers, the G4s in these Power Macs are old-school PowerPC 7455s, not the newfangled 7470s Mac watchers had anticipated. According to these naysayers, that limits bandwidth and takes some of the luster off the bidirectional performance of the DDR-RAM. So where does that leave us unregenerate Mac rumormongers? For the most part, looking away from Motorolas PowerPC efforts and at the intriguing developments from IBM, which is reportedly modifying its 64-bit Power4 processor (originally intended for the server market) to meet the AltiVec (a.k.a Velocity Engine) vector-processing specifications Macs ask for by name. Motorola may have precipitated a bit on Apples parade this time around, but the architectural advances these machines represent already make them a compelling purchase for serious Mac users. Oh, and one more bit of speculation for the road: If Apple succeeds in shaking up its PowerPC relationship in the coming months, the value of these hardware innovations will become much clearer very quickly. Are you ready to pony up for a new Power Mac? Drop me a line and tell me if these machines are all thator if youll stay tuned for the sequel. Mac veteran Matthew Rothenberg is online editor for Ziff Davis Medias Baseline and CIO Insight magazines.