Hardware Reference
In-Depth Information
measure aspects of processor and system performance. Although no single numerical measurement
can completely describe the performance of a complex device such as a processor or a complete PC,
benchmarks can be useful tools for comparing different components and systems.
However, the only truly accurate way to measure your system's performance is to test the system
using the actual software applications you use. Although you think you might be testing one component
of a system, often other parts of the system can have an effect. It is inaccurate to compare systems
with different processors, for example, if they also have different amounts or types of memory,
different hard disks, different video cards, and so on. All these things and more skew the test results.
Benchmarks can typically be divided into two types: component or system tests.
Component
benchmarks
measure the performance of specific parts of a computer system, such as a processor,
hard disk, video card, or optical drive, whereas
system benchmarks
typically measure the
performance of the entire computer system running a given application or test suite. These are also
often called
synthetic benchmarks
because they don't measure actual work.
Benchmarks are, at most, only one kind of information you can use during the upgrading or purchasing
process. You are best served by testing the system using your own set of software OSs and
applications and in the configuration you will be running.
I normally recommend using application-based benchmarks such as the BAPCo SYSmark
(
www.bapco.com
) to measure the relative performance difference between different processors or
systems.
Comparing Processor Performance
A common misunderstanding about processors is their different speed ratings. This section covers
processor speed in general and then provides more specific information about Intel, AMD, and
VIA/Cyrix processors.
A computer system's clock speed is measured as a frequency, usually expressed as a number of
cycles per second. A crystal oscillator controls clock speeds using a sliver of quartz sometimes
housed in what looks like a small tin container. Newer systems include the oscillator circuitry in the
motherboard chipset, so it might not be a visible separate component on newer boards. As voltage is
applied to the quartz, it begins to vibrate (oscillate) at a harmonic rate dictated by the shape and size
of the crystal (sliver). The oscillations emanate from the crystal in the form of a current that alternates
at the harmonic rate of the crystal. This alternating current is the clock signal that forms the time base
on which the computer operates. A typical computer system runs millions or billions of these cycles
per second, so speed is measured in megahertz or gigahertz. (One hertz is equal to one cycle per
second.) An alternating current signal is like a sine wave, with the time between the peaks of each
wave defining the frequency (see
Figure 3.1
).
