Speed isn't a measure of speed. That's Intel's message with its new naming scheme for its mobile CPUs. The company will soon bury the old, reliable gigahertz rating on its chips. Instead, if you're getting a PC with an Intel chip, you'll get a 300-, 500-, or 700-series model--much like BMW's car-naming scheme.

While it's true that clock speed tells you less than it used to about how well a particular chip will perform, this new scheme will likely confuse buyers more than it helps. Here's Intel's justification for it: According to Intel VP Anand Chandrasekher, speaking at the launch of the Dothan (a.k.a. 700 series) CPU last Monday, the new numbers are not about performance so much as "goodness."

Goodness me, that makes no sense
When I buy a car, I don't want to know how good the manufacturer thinks the engine is. I want to know how powerful it is--how much horsepower it has. Even BMW's cryptic naming scheme makes more sense than Intel's new plan, because the last two digits in most BMW model numbers indicate engine displacement in (a BMW 325 has a 2.5-liter engine), which is a pretty good indication of how much oomph the car has. By comparison, an Intel-series 745 chip runs at 1.8GHz. Do you see the correlation? Me neither. Because there isn't one.

Of course, with car engines, we care about linear things--horsepower and torque. With CPUs, we care about performance when playing games and performance when processing videos, and top-of-the-heap performance in one doesn't necessarily mean best-of-class in the other. But even so, fast is fast. What Intel is doing with its new scheme is taking into account other factors that have nothing to do with speed. For example, Chandrasekher says the new scheme takes into account power draw (and thus battery life).

It's like BMW naming its cars based on fuel economy.

This is a good thing to know, but it's like BMW naming its cars based on fuel economy.

Intel's new scheme also considers things such as cache size and bus speed, which do affect performance. And Intel has to do this. The problem, if it can be called that, is that the new Pentium M chips run faster than older Pentium Ms with the same, or even faster, clock speeds. So Intel needs to attach bigger numbers to the new parts to telegraph to consumers that they are faster.

This scheme also appears to be a shot at AMD, Intel's chief competitor. AMD's chip-naming scheme is grounded in its competition with Intel. For example, an AMD Athlon 64 3200 is sold as a direct competitor to an Intel Pentium 4 running at 3.2GHz--even though the AMD's internal clock speed is 2.2GHz. With Intel's new series-based naming scheme, AMD will have to figure out some new way to compete.

Pick a number, any number
Ultimately, just as engine displacement really doesn't equal horsepower (some engines wring more power out of less, and the number of cylinders and turbochargers and things like that throw off any displacement rating), because of the large impact of things such as the size of a processor's cache, CPU processor speed is meaning less and less in terms of performance. And Intel is working on dual-core processors, which will essentially (in theory) double performance at a given clock speed.

CPU processor speed is meaning less and less in terms of performance.

So what we need is an agreed-upon measure of processor performance. It doesn't have to be exact. Car engines are rated in horsepower, a performance measure the public understands, even though a car's overall performance will vary depending on a car's total weight and many other factors. Chips can be benchmarked on simple or complex tasks--from a raw number such as MIPS (millions of instructions per second) to something more real world, such as the BAPco SysMark tests we run on desktops and laptops.

I'd like to see the chip companies adopt a performance number from such a standardized test. It won't tell you precisely how well a chip will perform, but it will put you in the ballpark, just like a horsepower rating does. And it'd be a lot easier to decipher than an arbitrary number that seems destined to confuse buyers more than help them understand what it represents.

For more information on how these chips really perform, see our comparison of new Pentium M laptops, the first with the chips that carry the new names.