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CPU Upgrade Shootout
February 5, 2003 | Lucian Fong
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As long as Apple's Power Macs had been stuck at 500 megahertz, the CPU upgrade market was stagnant for even longer. Back in late 1999, Motorola hit a brick wall with the PowerPC 7410 processor (aka G4), which interrupted the product cycles of Apple and CPU upgrade companies. Even after Apple had surpassed the 1 gigahertz barrier in early 2002, the fastest G4 you could find in the processor upgrade aftermarket was 550 megahertz. For whatever reason (insert conspiracy theory of raving mad pro-Apple, anti-Motorola fanboy here), they did not take advantage of the faster G4s to come out of Motorola's foundries. Finally, in mid-2002, the two surviving CPU upgrade companies, Sonnet and PowerLogix reached the 1 gigahertz plateau.

Giga Designs jumped into the fray at Macworld San Francisco 2003 with their own lineup of fast G4 upgrades, selling them on the show floor through Other World Computing. We published a brief questionnaire with product manager Tim Ericksen, to find out their motivation for entering this volatile market. They plan to make a name for themselves with top-notch design and affordably priced products. Indeed, Giga Designs debuted their G4/1 GHz G-celerator upgrade at $550, which at the time, was $150 cheaper than competing products from PowerLogix and Sonnet. This ignited a price war between the companies, all to the benefit of consumers.

Understandably, gamers want to know if buying a faster processor will be worth the increase in performance, or simply, the price/performance ratio. To find out, I procured two G4 upgrades each from Sonnet and Giga Designs and ran them through a few simple real world benchmarks (AltiVec Fractal or Xbench not included), while observing performance during general use.

The Contenders
Sonnet and Giga Designs' upgrades are compatible with any AGP-equipped Power Macs as recent as the 2002 Quicksilver models, running Mac OS 9.2 or X. To install the Encore/ST in a Cube, you must buy a $30 installation kit from Sonnet. The Encore/ST automatically adjusts its bus speed to 100 or 133 MHz, while jumpers must be set on the G-celerator. No driver software is required for either upgrade to function.

Both companies provided me with each of their 800 MHz and 1 GHz G4 upgrade cards. Below is table of each card's vital specifications.

L2 CacheL3 CacheMSRPCube Comp.
Encore/ST G4 800 MHz256 KB2 MB DDR$400yes
Encore/ST G4 1 GHz256 KB2 MB DDR$600yes
G-celerator G4/800 MHz256 KBNone$300no
G-celerator G4/1 GHz256 KB2 MB DDR$550no

The 800 MHz G-celerator is $100 cheaper than the competing Sonnet card, but it lacks a L3 cache. Applications, and especially games, seem to be sensitive to the presence of a large L3 cache because they store data that is used frequently. Fetching data from the cache is much, much faster than doing so from the hard drive.

Also keep in mind that the PowerPC 7450 (the G4 used in current Power Macs and these CPU upgrades) and its revisions are, clock for clock, slower than the PowerPC 7410 (the G4 used in the original Graphite Power Macs). This means that given a PPC 7450 and a PPC 7410 of equal frequency, the 7410 will be faster. In designing a processor that was able to scale to higher frequencies, Motorola had to make several sacrifices; a lower IPC (instructions per cycle) being one of them. Hopefully, benchmarks will show the differences between the two G4 processors and how much (or how little) a L3 cache affects performance.



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