Q: I’m in the market for a new computer. The first item on the features lists is almost always “GHz.” What does that mean, and what’s a “Hertz,” anyway?

A: The short answer is that “Hertz” means “cycles per second” and “Giga” means “a billion.” The myth is that the higher the number of GigaHertz, the better, or at least faster, the computer is. But this is, indeed, a myth.

First, let’s have a (painless, I promise) refresher of 4th-grade powers of 10. Kilo means multiply by 1000, mega means a million, giga mean a billion, tera means a trillion, peta means a quadrillion, etc… Each of these is a thousand times greater than the previous. So, a gigathingy is 1000 megathingies, and a megathingy is 1000 kilothingies. (Therefore, kids, a gigathingy is a million kilothingies, or a megakilothingy, or something like that).

We can go the other way, too (metrically speaking). One one-thousandth of a thingy is a millithingy. A millionth is a microthingy, a billionth is a nanothingy, and a trillionth is a picothingy. We computer geeks like to break down seconds into teensy-tiny parts, like nanoseconds and picoseconds. We’ll come back to these.

Now let’s talk about what a “cycle per second” is. We see the term Hertz used in audio and music, and in electromagnetic waves, like radio. Sound is a vibration of the air. One vibration is a cycle. The simplest form of sound is a sine wave. Combining sine waves gives a more complex sound. The faster the vibration, the higher the pitch. 440 Hertz is the note A above middle C and is the standard for tuning instruments. Middle C is 263 Hertz. Humans can hear just about to 20kHz (that’s 20 kiloHerz or 20,000 Hertz).

Radio waves and other electromagnetic waves are waves of energy and are more often measured in kHz, MHz (megaHertz), and GHz (gigaHertz). AM radio (remember that?) broadcasts in the range of 535 kHz and 1605 kHz and FM is in the range 88 MHz and 108 MHz. Microwave ovens cook food by bombarding them with electromagnetic waves at a frequency of around 2.5GHz.

Some kinds of electricity also are measured in Hertz. The stuff that comes out of your electrical outlet is alternating current, and its frequency is 60Hz (50Hz in Europe). The stuff that comes out of a battery is direct current and has no frequency.

Now that we’ve beat around the bush, let’s talk about what Hertz has to do with computers. But first, why do we say “Hertz” and not “cycles per second?” “Hertz” is named after Heinrich Rudolf Hertz, a German physicist who figured out that that electricity can be transmitted in electromagnetic waves, thus setting the scene for the invention of radio. (It’s a little-known fact that his younger sister, Avis, invented the rental car).

Finally, let’s talk about computers.

Simply put, the GHz of a computer refers to the clock speed, or, ostensibly, the number of “things” it can do in a second.

Many people are under the mistaken impression that the GHz of a computer is all they need to know about the speed and abilities of a computer. Those people couldn’t be any farther to the truth. The fact is, the GHz rating of a computer is more like the RPM of an automobile engine. Just because it is revving fast does not necessarily mean that it’s getting a lot of work done. In a car, you don’t really care about RPM. You want to know horsepower (which you also have to be careful of, since a heavier car might be slower than a lighter car with the same HP), torque, and real measures, like 0-60 acceleration and quarter mile time and speed.

Well, in this respect, computer performance has a lot in common with car performance. The clock speed of the processor tells on a small part of the story. There are a lot of factors that go into the actual performance and abilities of a computer. In fact, Intel has announced that it will stop naming its Pentium processors by the speeds. AMD has already stopped doing this. It was just too hard to explain to people that a 1.6GHz Centrino is faster than a 2.6 Celeron.

In my next article, I’ll explain why this is the case and what kinds of things factor into the performance of a computer.