How It Works: CPU

Both companies make models for high-end, midrange, and low-end machines. Other companies produce CPUs as well, such as Motorola's Power PC 750 which powers Macintosh computers.

AMD's Athlon and Intel's Pentium III share the pinnacle of power for CPUs that run Microsoft's Windows operating system. They are roughly comparable in design and performance, both including enhancements that speed up 3D games and computer-aided design software.

Intel and AMD's high-end CPUs power a wide range of PCs, from midpriced home systems (in the 600- to 850-MHz range) to the most expensive engineering workstations and high-end multimedia systems (around 866 MHz and above). In the newest models, the CPU represents anywhere from around $200 to about $1000 of the system cost.

On the high end, PCs with 1-GHz chips will run about $2700 to $3300, depending on what other components the PC offers. In the middle range, systems powered by 600-MHz to 850-MHz chips from AMD or Intel cost from about $900 to more than $1600.

Economy-priced (sub-$150) chips usually run at slower clock speeds than Athlons and PIIIs, have smaller or slower caches, and have fewer performance enhancements. AMD's K6-III and K6-2 and Intel's Celeron anchor low-end PCs selling for less than $1000.

Portable computers often can't handle the fastest CPUs. A desktop design can dissipate heat much better than a laptop can, which means laptops have to use slower and less powerful CPUs. Faster processors also require more power to run, which eats up battery life. Currently, the fastest portables available run at about 700 MHz.

Looking Ahead

CPU makers are always making changes to improve performance. Recently, they've moved from a fabrication process called .25 micron to the new .18 micron, which allows closer spacing between smaller transistors, and thus provides higher speeds and less heat from the same architectures. In addition, the aluminum interconnects between transistors are beginning to be replaced with copper, which conducts electricity better than aluminum.

But these enhancements don't mean the push for more raw speed won't continue. Intel has announced a new chip, codenamed Willamette, that will run at 1.5 GHz and should be available later this year. AMD has promised to keep pace.

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David Essex

PC World
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