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Intel now knows how the United States felt in 1957 when the Russians beat America into space with Sputnik.

For years, Intel dominated the CPU speed race. But on March 6 of this year, the unexpected happened. Several months ahead of schedule, AMD surprised the world and launched the first x86 CPU to require a whole new term for blazing speed: gigahertz.

The famously competitive Intel must have seethed as AMD grabbed the glory. At the time it got wind of AMD's plans, the chip giant was busily preparing to launch its 850- and 866-MHz Pentium III chips. Intel hastily regrouped and on March 8 announced its first 1-GHz PIII processors. Intel does win bragging rights for the quickest 1-GHz processor--by a sliver.

First Tests

We tested 1-GHz Athlon machines from Compaq and Gateway for this story, plus a 1-GHz PIII machine from IBM. On our PC WorldBench 2000 tests, the Intel-based IBM PC ran a slim 5 percent faster than the number two machine, Gateway's Athlon system. Intel's 1-GHz chips will ship in limited quantity until the third quarter, which means you'll be able to buy systems from only a few companies, including Dell, HP, and IBM. AMD, meanwhile, should have plenty of 1-GHz Athlons to go around, several PC vendors told us.

In the 1-GHz glare, don't lose sight of the other new chips: 850-, 900-, and 950-MHz Athlon systems will be shipping when you read this, as will 850- and 866-MHz PIIIs. We tested Athlon-850 machines from Compaq, Cybermax, and Gateway, plus a Dell PIII-866 system that runs nearly as fast as the IBM 1-GHz machine. These 850- and 866-MHz machines may offer a better balance of price and performance for many people. Compaq's 1-GHz Athlon PC, for example, runs 11 percent faster than the company's 850-MHz model but costs hundreds of dollars more.

Big Boost?

Do you remember PCs that ran at rates slower than 100 MHz? If so, you can't help but marvel at the megamilestone of 1000 MHz.

But understand this: While Intel and AMD are pushing CPU clock speeds ever higher, 800- to 1000-MHz systems are clustering pretty close to each other on our application-based performance tests.

For systems today, CPU speeds simply don't tell the whole performance story. A CPU acts as a system's brain, but backbone components like main memory, the system bus, and the graphics card do a lot of heavy lifting. These components can noticeably speed up or slow down a PC. More than ever, it's important to take into account the differences inside these boxes--and not just the MHz ratings outside.

Of the seven systems tested here (all running Windows 98 SE), IBM's Aptiva S Series GZ earned the top score of 165 on PC WorldBench 2000. (This updated version of our benchmark suite uses 11 applications, including Word, Excel, Netscape Navigator, Quicken, and PhotoPaint. You'll also see WorldBench 2000 at work in this month's Top 100 desktops reviews.) Gateway's Select 1000, carrying a 1-GHz Athlon, clocked in at 157; and the Pentium III-866 computer, Dell's Dimension XPS B-866, earned 156: Those figures add up to a virtual dead heat, despite the Dell's slower clock speed. The Compaq Presario 5900Z-1GHz earned a similar score of 154.

Note that the Dell and IBM systems have 128MB of Rambus memory (RDRAM), while the 1-GHz machines from Gateway and Compaq have 256MB of SDRAM. To date, Rambus memory hasn't made much of a difference on our benchmark tests, but Intel has said the benefits of Rambus will become more evident as CPU clock speeds increase. That's an assertion our tests may already be starting to support. Unfortunately, RDRAM still costs the PC manufacturer about 30 percent more than standard SDRAM.

More importantly, the Athlon chip's off-die Level 2 cache (as opposed to an L2 cache on the same piece of silicon as the CPU) limits system performance gains. The 1-GHz Athlon chip's Level 2 cache runs at one-third of the chip's clock speed, while Intel's Coppermine PIII chips have an on-die Level 2 cache that runs at full speed. Our tests show that the on-die L2 gives a speed jolt to everyday applications like those used in PC WorldBench 2000. You can expect big performance gains when AMD releases its next Athlon, code-named Thunderbird, with an on-die L2 cache; Thunderbird is due out sometime between April and June.