Link to PC Magazine Article - and Article on INTEL, AMD, POWER PC, et al. Development
The url for the "first looks" review of the Power Mac G4 1.25 is:
http://www.pcmag.com/article2/0,4149,810846,00.asp
There is another article in this month's PC MAGAZINE that you and others might find interesting as well. The article is a roadmap of CPU development. Designs for - and the future plans of - Intel, AMD, the PowerPC (Moto and IBM), Transmeta, and VIA are discussed.
What makes the article so interesting is that it breaks down how the different processors work so that we finally understand why exactly it is that clock speed is not the single biggest factor in processor performance. For example, it explains that creating a longer pipeline allows for the clock speed to be ramped up, giving us the P4 at 3.06 GHz. But it also explains that while a longer pipeline means higher clock speeds, it also means more errors in the anticipation process that goes on inside the chip. That means that a processor with a long pipeline (20 stages) like the P4 needs all that speed to try to get it right. A short pipeline - the Athlon XP has a 10-stage pipeline - will make fewer errors in many types of applications - therefore, each clock tick is more efficient. The current PowerPC G4 has a seven-stage pipeline and is even more efficient. It comes down to: while a shorter pipline limits possible clockspeed, a shorter pipeline needs a lower clockspeed to match the performance of a higher speed, longer pipeline chip.
This is all very interesting when you consider that in Intel's high-end chips (ITANIUM 2), the speed falls from 3.06 GHz down to 900MHz or 1 GHz! Of course Intel is not putting less powerful processors into its scientific workstation offerings, but is using more efficient designs (which also incorporate either a 1.5 or 3 mb Level 3 cache). Back at the consumer level, there is a note that the next generation of Pentium notebook chips - Banias - "won't achieve the higher clock speeds of the P4 because it lacks a 20-stage-pipeline. Intel says, however, that Banias will outperform the P4. Sound familiar? Intel has stated that it will not use a part-numbering scheme like AMD's and will market Banias in terms of its performance without hiding clock speed."
The in-print version of this article appears in PC MAGAZINE at pages 117-128 of the Feb. 4, 2003 issue now on the stand. The electronic version can be found at:
http://www.pcmag.com/article2/0,4149,806465,00.asp
Although I don't know if the web version includes all of the explanatory sidebars and insets that make the CPU Roadmap article so helpful.
(small update - the web article does have a little box to the upper-right that has the extra inset features found in the print version)
