How to choose a microprocessor

Question: I was wondering if you would cover the pros and cons of Celeron vs. Pentium III. I have been told not to buy Celeron. Can you comment? —R.S.

Answer: I’ll go a couple better and cover all three chips being offered by Intel, including the Celeron, the Pentium III, and the Pentium 4, plus I’ll give you an overview of AMD’s Duron and Athlon chips.

The Pentium 4 is Intel’s latest line of microprocessors (for the uninitiated, the microprocessor is the brain of a computer). The P4 has 42 million transistors in it, whereas the PIII and Celeron have 28 million. The rule of thumb is the more transistors, the faster the chip.

The P4 have clock speeds starting at 1.3 gigahertz up to 1.7 GHz at the time of this writing. By the end of 2001, you’ll see 2 GHz chips and eventually 3 GHz. By comparison, the fastest PIII has clock speed of 1.13 GHz. A gigahertz is 1,000 MHz. So a 500 MHz chip runs at half a gigahertz.

Clock speed refers to the rate at which a computer executes instructions. The faster the clock speed, the more instructions the computer can execute per second.

Clock speed is a good rule of thumb for comparing chips. This is not absolute, though, because there some key components in a computer beyond the clock speed—including memory, the system bus, and cache—that affect performance. More about that in a minute.

AMD, the main competitor to Intel in PC processors, makes two lines of chips. The Duron, the company’s budget chip, goes head to head with Intel’s Celeron. AMD also makes the Athlon chip, which competes with the Pentium III and Pentium 4 chips. The Athlon currently tops out at 1.4 GHz.

New Celeron chips have clock speeds of up to 850 MHz as of spring 2001. The AMD Duron chip runs as high as 950 MHz.

If you’re in the market for a new computer and are wondering which chip you should buy with your new PC, here’s the skinny: AMD typically competes on price. The Duron is generally less expensive than the Celeron.

The Athlon is less expensive than the Pentium chips. If you’re after a budget computer that does word processing and Internet surfing well, then a Celeron or Duron computer will serve you well. Be aware, however, that advances in computer software and new functions added to computers in the future will quickly overwhelm your Duron or Celeron computer.

If you plan to buy a new computer every 18 months and just want it for light computing tasks then, these chips may do just fine. If you buy a new computer every two to four years, and like to do heavy duty multimedia tasks like voice recognition, MP3 music file creation, and video and picture editing, you’ll be best served by looking at the Athlon, Pentium III, or Pentium 4 chips.

The Pentium 4 chips are especially tuned for multimedia functions. The Athlon also gets rave reviews. Currently AMD is making claims that their 1.4 GHz Athlon chip out performs the Pentium 4 chip at 1.7 GHz. Is this true? It’s hard to say.

Any mainstream user may notice incremental differences among the top-end chips. Mostly these wars are about marketing and corporate positioning. A fast chip is a fast chip. So if you want multimedia functionality, either of these chips will do you. In fact, often a computer with a slower chip and more RAM (How to Add RAM) is preferable to a faster chip with less RAM. (RAM, as a refresher, is a set of computer chips that crunches data when it’s told to by the microprocessor.)

The other consideration when buying a new computer is the system bus on the motherboard. The bus is a set of circuits that moves data between the various parts of a computer.

A slow bus can create a bottleneck in data processing. Think of the system bus as the public roads that connect two race tracks. A race car can zip around the track at super fast speeds, but to get to another race track via public roads it has to slow down. These public roads are the computer’s system bus. The race tracks, in this example, are the processor and memory.

A Pentium 4 uses a 400 MHz system bus. The PIII uses a 133 MHz bus. The Celeron uses a 100 MHz bus. The Athlon uses a 266 MHz bus, while the Duron uses a 200 MHz bus.

Then there’s the issue of cache memory. You see two types of cache referred to in systems specs: L1 (or level one) cache which is memory integrated into the processor, and L2 (or level two) cache which is external to the processor chip. These are holding areas for data before it is processed.

The advantage to having more cache means that more data is readily available to the chip when it needs it quick.

If you’re making carrot soup, it’s more efficient to have carrots (data) in the kitchen by the sink (the cache) and not out in the vegetable garden (the hard drive). The bigger the sink, the more carrots you can have available to make your soup and the faster you get to lunchtime.

You’ll find that the Pentium III/4 and Athlon have more cache than the Duron and Celeron.

But let’s get practical. This information is useful only in the context of buying a computer.

Here’s how I buy a computer. I like to employ the “second best rule”. Choose a computer that has the second or third best processor on the market. Find a computer package that offers all the parts you need and a good value for your dollar compared to the competition. Also, make sure you get lots of RAM installed. Aim for 256 MB if you can afford it.

Also, make sure there is space in the computer to add RAM in 18 months. If you follow those guidelines, you’ll not be disappointed.

To find different CPU’s (processors), you can visit and search for what they have to offer.