Published May 2005

Clock speed alone doesn’t
determine laptop’s worth

By Lionel Contreras
Guest Columnist

I had some friends ask me recently why one laptop, which operated slower than others even though it had the same programs, was the more expensive one. The answer can be found in a combination of clock speeds, chip architecture and power usage.

Let’s start with clock speeds and chip architecture. Say you have one of those old analog stopwatches, the ones with the microsecond hands. Now, let’s say that each one of those hand ticks constitutes a CPU clock cycle. In a computer, those clock cycles are measured in clock speeds such as megahertz (MHz) or gigahertz (GHz).

Now, just because one computer has a faster clock speed than another does not ensure that the information you are working on will be processed faster. Apples are a classic example.

Say your Apple G4 has a 1.2-GHz processor, but the newer G5 has an 800-MHz, or 0.8-GHz, processor. Why is the G5 faster? Well, in terms of chip architecture, there’s a 32-bit processor in the G4 and a new, 64-bit processor in the G5.

So the old G4 gets 1,200 clicks at the same time the new G5 gets 800 clicks. But the 1,200-click G4 processes 32 bits per click, whereas the 800-click G5 processes 64 bits per click.

Here’s the basic math:

• The G4: 1,200 multiplied by 32 equals 38,400 bits.
• The G5: 800 multiplied by 64 equals 51,200 bits.

Now apply that math to the time it takes to draw an image of Pac-Man, which takes 50,000 bits. The G4 has to do almost two clock cycles, while the G5 takes less than one clock cycle.

This example shows that clock speed is an important feature to consider — only if you are talking about computers with the same chip architecture. Remember to look at the chip architecture as well as the clock speed.

Now, back to the question of why a slower laptop costs more than a faster one: Well, it’s about power, literally.

A chip that runs slower uses less power, and a chip that rests between jobs uses even less power. It’s the difference between getting eight to 12 hours of usage on a laptop instead of two to four hours of usage.

Some of the cheaper laptops use chips that are not optimized for power usage. It’s like turning your engine off at each red light, it saves gas. Desktops don’t do that; laptops do, so the processor is asleep until it needs to do something — and the machine’s power isn’t being drained.

If you don’t plan on having any extended time away from an outlet, go for the cheaper laptop that’s running faster. If, however, you are truly wireless, get the more expensive one that runs slower with multi-clock speeds. When the battery gets low, it automatically steps things down to squeeze in those extra hours you need.

To compare chips, go to http://developer.intel.com/products/processor/index.htm.

Lionel Contreras is an information systems technician with The Herald.

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