Hardware Reference
In-Depth Information
different amounts or types of memory, different hard disks, different video cards, and so
on. All these things and more skew the test results.
Benchmarkscantypicallybedividedintotwotypes:componentorsystemtests. Compon-
ent 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
measuretheperformanceoftheentirecomputersystemrunningagivenapplicationortest
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.
Inormallyrecommendusingapplication-basedbenchmarkssuchastheBAPCoSYSmark
( www.bapco.com ) to measure the relative performance difference between different pro-
cessors or systems. The next section includes tables that show the results of SYSmark
benchmark tests on current as well as older processors.
Comparing Processor Performance
A common misunderstanding about processors is their different speed ratings. This sec-
tion covers processor speed in general and then provides more specific information about
Intel, AMD, and VIA/Cyrix processors.
Acomputersystem'sclockspeedismeasuredasafrequency,usuallyexpressedasanum-
ber ofcycles per second. Acrystal oscillator controls clock speeds using a sliver ofquartz
sometimes housed in what looks like a small tin container. Newer systems include the os-
cillator circuitry in the motherboard chipset, so it might not be a visible separate compon-
ent 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 em-
anate 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
computeroperates.Atypicalcomputersystemrunsmillionsorbillionsofthesecyclesper
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 ).
Figure 3.1 Alternating current signal showing clock cycle timing.
 
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