Computer shoppers looking for performance have fallen into trap of the Megahertz Myth.
Buying a new computer system can be as tough as buying a new car.

When you buy a car, you ask about horsepower, then hop on the freeway to see how much get-up-and-go the car really has.

But in the end, speed probably won't be your deciding factor. You'll want to see how it handles, test the sound, steering, brakes, smooth ride, etc. It's a combination of things that makes a car a winner.

Buying a new computer should be the same. But it isn't. Many consumers continue to gauge a computer's performance on one thing alone: how fast the microprocessor is.

That way of thinking needs to change, according to the folks at Apple Computer and Advanced Micro Devices, the Sunnyvale-based chip maker that's one of the biggest competitors to Intel, makers of Pentium chips.

Computer shoppers have fallen into a trap called the Megahertz Myth.

Megahertz (MHz) and now gigahertz (GHz) are the measurements used to determine the clock speeds of the processor, or the speeds at which information moves through a computer's microprocessor. The clock speed is the big number you'll find at the top of computer advertisements in the Sunday paper. For example, a PC might come with a 900 MHz AMD Athlon chip or a 1.7 GHz Pentium 4 chip. A Power Mac might have a 867 MHz G4 chip inside.

In the early days of personal computers, faster was better, said Mark Bode, a marketing manager at AMD. That's because processors were built -- and upgraded -- under the same basic architecture.

But as technology advanced, the architecture of the chip changed -- and comparing chips on speed alone was no longer even. Today, even comparing a Pentium III and a Pentium 4 running at the same speeds isn't fair. Intel changed the architecture of the Pentium 4 to work better with new hardware and software. Some of it anyway.

That's AMD and Apple's point. Consumers can't look at that Sunday ad or the retail shelf at Best Buy and compare the AMD Athlon to Apple's G4 to the Pentium family of chips.

``You have to look at the end results, how the application runs,'' Bode said. ``That's why you bought the PC. How does it work for you? How does it do the things you want it to do?''

Apple argues that speed only tells you how fast the work is being done -- or how many cycles per second the processor engine spins. But it doesn't go into how much work is being done by the processor during every clock cycle.

``It's like moving sand,'' said Jon Rubenstein, Apple's senior vice president of hardware. ``You have to look at how big the shovel is. You need fewer cycles to complete the job if you have a big shovel.''

At the Macworld convention in New York this summer, Rubenstein demonstrated the Megahertz Myth with results of a comparison of a 867 MHz Power Mac G4 to a 1.7 GHz Pentium 4 machine running Adobe Photoshop 6.0.

The Mac, he said, handled the application 58 percent faster than the PC.

Intel isn't arguing those results but warns consumers to react cautiously to such conclusions.

``There's a lot of tweaking you can do'' to make a chip perform better with some applications than others, said Intel spokesman Manny Vara. ``If you tune a specific software application to work well with a particular piece of hardware, I can't say that's wrong. If you run a Photoshop filter four times faster, what you've proven is that you can run that filter four times faster. That doesn't mean others will run faster.''

Chip manufacturers do that sort of tweaking -- not to be deceptive, he said, but to enhance the performance of particular applications.

``You can show that any machine is faster than any other machine with any particular operation,'' Vara said. ``They can claim that the Mac is faster than the Pentium 4 at any particular thing but I can find seven or eight things where the Pentium 4 can beat the Mac.''

With all the back and forth banter, you'd think the companies don't see eye-to-eye on anything. But each agreed that consumers should be asking less about speed and more about what they'll be doing with a computer.

``People are trying to figure out what to do with all that gigahertz,'' Apple's Rubenstein said. ``They don't need them for Excel spreadsheets. They need them for multimedia applications -- video editing, handling music. Those applications run much better on a Mac.''

To a certain extent, Rubenstein is right. But advancements in the AMD and Pentium chips are making those applications easier for PC users, as well.

The point remains, though, that consumers don't need a 2 GHz chip to send e-mail, browse the Web or run a spreadsheet -- and they shouldn't drop money on a top-of-the-line system if that's all they'll be doing.

So how does one shop if not by comparing the MHz of the machine? And, more importantly, what alternatives do Apple and AMD propose?

Consumers should be looking at the whole picture -- the chip, hard drive capacity and the amount of memory, as well as the performance of the graphics card and available ports for printers, scanners and other add-ons.

For now, AMD is launching its newest chip -- the Athlon XP -- with a model number attached instead of clock speed. For example, the clock speed of the Athlon XP 1800+ is 1.5 GHz. AMD says it is really the equivalent to a 1.8 GHz Intel chip and does more work than a 2 GHz Intel chip on some applications -- at half the cost.

Consumers won't know the clock speed based on a ``model number.''

Still, it's a step in the right direction, said Kevin Krewell, a senior analyst with MicroDesign Resources in San Jose. Likewise, a move by PC manufacturers to market specially configured computer systems as being ideal for gamers or music enthusiasts or photo hounds could be another way of changing the way consumers shop.

``It's ripe with possibilities of misinterpretation by the consumer,'' he said. ``But it's the consumer's responsibility to investigate this and do a bit of research. They need to read some reviews and check out some Web sites before they buy. A little bit of education can go a long way.''