Over the history of the PC, one dominating factor that influences which computer to buy, is the speed of the CPU measured in MHz. This is a major reason why Intel has dominated the market for a very long time. The performance of a CPU does not depend solely on the MHz. The MHz speed, or Frequency, is merely one of the contributing factors.

For a CPU to be fast, it has to have a combination of fast frequency (MHz), efficiency in calculations (FPU and ALU), a bus as wide as possible (currently 32-bit, although Intel and AMD are already working on 64-bit models) as well as a pipeline which has to be as short and efficient as possible. The longer the pipeline, the more time it takes for the CPU to output data. The AMD Athlon has an excellent FPU, which gives its "slower" CPU an edge over the faster clocked Intel Pentium 4. The Athlon also features a shorter, more efficient pipeline, which makes it an excellent choice for personal and professional computers.

To demonstrate how a CPU benefits from a shorter pipeline, here is a basic model of data being processed to make a picture. There are two pipelines (one long and one short) to illustrate the advantages of an efficient pipeline.

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Now, you might be thinking, "Wait a minute, if the CPU with the shorter Pipeline runs at a slower pace, wouldn't the higher-clocked CPU eventually catch up to the slower CPU?". In a perfect world, this might be true, but just like everything, CPU's are not perfect.

When a CPU is fed data, there are sometimes branches of data which causes a pipeline to drain. Although this does not happen very often, you must remember that there are millions of pieces of data being fed to the CPU every second, and a large amount of the data can contain bad parts. To illustrate how this impacts a CPU with a longer pipeline more than a CPU with a shorter pipeline, we will once again be using two CPUs. The CPU with the longer pipeline will be running at 150% the clock speed of what the CPU with the shorter pipeline will be running.

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We hope that you now have a bigger understanding of why the CPU speed cannot be measured in MHz.