Choose Your Processor for Speed

You should consider the processor speed when buying a new computer or
upgrading. The processor is called the central processing unit or CPU. It is
a chip on the mainboard.

Last time we discussed adding memory as a way to speed up your computer. If
you have reached maximum effect by adding memory, the next thing to do is
add a faster processor.

A processor upgrade may not be possible. If your computer is more than two
or three years old, it may not be capable of accepting the current CPU
design. The older CPU in a faster model may no longer be available for it.
Also, your present CPU may be the fastest your mainboard will accept.
However, selection of the CPU is of prime importance when buying a new
computer.

Some new computers have full-featured CPUs, and some have reduced-featured
CPUs. Reduced featured CPUs include the late AMD Duron and the Intel
Celeron. These CPUs are normally used in low-end or economy computers.

In selecting your CPU, you will find a direct correlation between price and
performance. Price will range from abut $70 for a 32 bit, 1.2 GHz CPU to
about $700 for a 64 bit, 3.4 GHz CPU. There is a price / performance break
somewhere between. That break is currently a 32 bit CPU running 2.0 to 2.4
GHz. Be aware that you will pay a real premium for performance above the
price break, and the price of your configuration will drop drastically in
the future.

Now here's a technical lesson. CPU performance is gauged by data throughput,
which is determined by many factors, but primarily by data width, which is
expressed in bits, and frequency, which is measured in Hertz. One Hertz is
one cycle per second. A 3 GHz (Gigahertz) CPU has a frequency of 3 billion
cycles per second, and will process one bit of data per cycle for each bit
width. Most of the current CPUs are 32 bit processors, so 32 bit width times
3 GHz equals 96 billion bits per second. There are 8 bits in one byte, which
represents one character or letter. A word is defined as 5 characters.
Therefore, a 3 GHz, 32 bit CPU will process about 2.4 billion words per
second.

It is as difficult to grasp this processing rate as it is to grasp the
dollars in the national debt.

For interesting comparisons, the AC (alternating current) electricity in
this county alternates at a frequency of 60 Hz. Under some conditions, you
can see this vibration. A "C" tuning fork vibrates at 256 Hz. You can feel
this vibration, but not see it. Now try to imagine something vibrating at 3
GHz!

Also affecting CPU throughput are the internal architecture of the CPU chip
and its bus speed. The AMD chip has a slightly more efficient architecture
than the Intel, thus giving it an edge on throughput.

Data width will become more of a factor in the near future. Both Intel and
AMD now have 64 bit CPUs on the market. When the IBM PC first came out in
the early 1980s, it had an 8 bit CPU running at 4.77 MHZ. You do the math.

In summary, if your older computer is more than three years old, the CPU is
on the cusp of being ungradable. If it is more than five years old, it is
not economically feasible to upgrade the CPU. You might get some more speed
by upgrading the memory.

If you are shopping for a new computer, be aware that the cheapest may have
reduced-featured CPUs, that there is a price/performance break at around a
32 bit CPU running 2.0 to 2.4 GHz, and that you will pay a premium for
anything faster. If price is not a factor, then go for it and get the
biggest, fastest CPU available.