words CPU and
microprocessor are used interchangeably, in the world
of personal computers (PC), a microprocessor is actually a
that contains a CPU. At the heart of all personal computers sits a
microprocessor that controls the logic of almost all
digital devices, from clock radios to fuel-injection systems for
automobiles. The three basic characteristics that differentiate microprocessors
are the following:
- Instruction set: The set
of instructions that the microprocessor can execute.
- Bandwidth: The number of
bits processed in a single instruction.
- Clock speed: Given in
megahertz (MHz), the clock speed determines how many
instructions per second the processor can execute.
The higher the value, the more
powerful the CPU. For example, a
32-bit microprocessor that runs at
50MHz is more powerful than a
16-bit microprocessor that runs at
If you think overclocking sounds like an ominous term, you have the right idea. Basically overclocking means to run a
microprocessor faster than the
clock speed for which it has been
tested and approved. Overclocking is a popular technique for getting
a little performance boost from your system, without purchasing any
additional hardware. Because of the performance boost overclocking, is
very popular among hardcore 3D
Most times overclocking will result
in a performance boost of 10 percent or less. For example, a computer with
Pentium III processor running at 933MHz could be configured
to run at speeds equivalent to a Pentium III 1050MHz processor by
increasing the bus
speed on the motherboard. Overclocking will
not always have the exact same results. Two identical systems being
overclocked most likely will not produce the same results. One
will usually always overclock better than the other.
Key Terms To
Abbreviation of central processing unit. The CPU is the brains of
To run a microprocessor faster than the speed for which it has been
tested and approved.
The bus that connects the CPU to main memory on the motherboard.
Overclocking Related Terms
To overclock your CPU you must be quite
familiar with hardware, and it is always a procedure
conducted at your own
risk. When overclocking there are some problems and issues you'll
have to deal with, such as heat. An overclocked
CPU will have an increased heat output, which means you have to look at
additional cooling methods to ensure proper cooling of an overclocked CPU.
Standard heat sinks and fans will
generally not support an overclocked system.
Additionally, you also have to have some understanding of the different types
of system memory. Even though your CPU can be overclocked, it doesn't mean your
modules will support the higher speeds.
Common CPU Overclocking Methods
The most common methods of overclocking your CPU is to either raise the
multiplier or raise the
while not the only options they are the most common. To understand overclocking, you have to understand the
basics of CPU speeds. The speed of a CPU is measured in Megahertz (MHz) or
Gigahertz (GHz). This represents the number of
clock cycles that can be
performed per second. The more clock cycles your CPU can do, the faster it
The formula for processor speed is:
frontside bus x multiplier = processor speed.
Pentium III 450MHz
The CPU runs at 450 million clock cycles per
second. The CPU runs at at a speed of 450 megahertz. Using our processor
speed equation we have: 100MHz (frontside bus) x 4.5 (multiplier) =
450MHz (processor speed)
The frontside bus connects the CPU to the
main memory on the motherboard basically, it's the conduit used by your
entire system to communicate with your CPU. One caution with raising the FBS is that is can affect other system components. When you
change the multiplier on a CPU, it will change only the CPU speed. If you
change the FSB you are changing the speed at which all components of your
system communicate with the CPU.
Using our example above, the multiplier is
4.5. Since valid multipliers end in .0 or .5, you could try increasing the
multiplier to 5.0 to obtain a performance boost (which would result in
100MHz x 5.0 = 500MHz). By far the easiest way to overclock a CPU is to
raise the multiplier, but this cannot be done all all systems. The
multiplier on newer Intel CPUs cannot be adjusted, leaving Intel
overclockers with the FSB overclocking method (because of this AMD is
becoming more of a popular choice for overclockers). The equation formula doesn't change for the
method of raise the FSB. In the example above the FSB was 100MHz. Raising it
to 133Mhz would change the equation (133Mhz x 4.5 = 598.5 MHz).
Sometimes overclocking can be that simple --
other times it's not.
Depending on your motherboard, overclocking is
done one of three ways: by changing
jumper or dip-switch settings
(from .on. and
.off. or .close. and .open.), by
changing some of the Chipset Features settings
in your BIOS,
or by using a combination of both. In overclocking you will need to know
your hardware, plan your overclocking method, and, of course perform many tests
once changes have been made. You may
need to adjust your CPU voltage, and you will most likely have to try several settings before obtaining a successful
and stable overclock result.
Overclocking Risks (and There Are Many)
Overclocking comes with many risks, such as overheating, so you should
become familiar with all the pros and cons before you attempt it.
Additionally, overclocking isn't supported by the major chip manufacturers
which means overclocking your CPU will void your warranty. Overclocking can
also decrease the lifespan of the CPU, cause failure in critical
components and may even result in some data corruption. You may also notice
an increase in unexplainable crashes and freezes.
You can find many complete step-by-step guides available
online that detail the actual process of overclocking. If you've decided to
take the plunge and overclock your CPU, we recommend you don't start with
your only usable system (try using outdated and cheap hardware to practice
with) and be sure to find a knowledgeable source and read some of the
overclocking information and
Web pages listed
below in the links section to get you started in the right direction.
Did You Know...
"Multiplier locking forces the CPU to use a multiplier that is
preset by the manufacturer. Intel has been quoted as saying they
use multiplier locking to prevent unscrupulous retailers from
overclocking processors to higher speeds, and selling
overclocked systems to consumers for the same, higher price as the
faster retail model."
Vangie 'Aurora' Beal
Last updated: September 16, 2005
Overclockers New Zealand Forums
New Zealand Forums
An excellent FAQ with instructions, descriptions, and background information on
overclocking a CPU. Provides example changes and an excellent plan and test
section. This FAQ was referenced in our article.
SysOpt Overclocking Database
Search through the data to find out the "overclockability" of various hardware
Tom's Blurb: Overclocking
AMD's Socket A Processors
I've got even two things to report for the ones of you who don't just fancy
AMD's new Duron and Athlon/Thunderbird processors because they are good
performers for a fair price, but who like to tweak some more speed out of them
The FiringSquad - Home of the Hardcore Gamer
The first big steps towards overclocking were made in the Pentium era. During
this time, typical neighborhood techies discovered that a Pentium 75 was nothing
more than an underclocked Pentium 90. Soon, people were taking Pentium 133s and
turning them into 166s, and in turn 166s soon became 200s. When the 233MMX made
an entrance, it soon became obvious that the chip had little trouble reaching
250MHz or 266MHz.
Overclocking: Celeron D 335 vs. Sempron 3100+
It has been a long time since both Intel and AMD released value processor lines
with so much promise. Both the Celeron D and Sempron (Socket 754) models are
variants of popular high-end core designs, and not only provide a nice
performance increase over last-generation designs, but look to have serious
Hardware Central - CPU Overclocking
Overclocking is going mainstream, it seems, among end users. Almost all hardware
Web sites discuss the subject, and most make it seem like it's easy, and that
everyone does it. Of course, manufacturers don't want you to do it to their
processors, so you probably won't find it mentioned in magazines. But, on the
Internet, it runs rampant. In many cases, though, you don't get the real story
Pentium 4 Northwood Overclocking Guide
The Pentium 4 Northwood core provides the required "new core" ingredient, while
many highly overclockable and 533 MHz-compatible platforms give users a great
overclocking base to work with.
This article reviews the essential notions and basic steps on How To overclock
Gamer God - Keeping it
An excellent overview of Cooling.
HelpOverclocking.com - JUMPERS
The two values that determine the speed of the processor (frequency of the bus
or clock and multiplier) are found on the motherboard. The method used to change
them depends on the model of motherboard itself.
Athlon XP Overclocking Guide
This Athlon XP Overclocking Guide will take you through the two main
overclocking methodologies, and give you the basic steps you'll need to either
start your overclocking journey or just refine your current system setup.
Processors Frequency ID Utility
The Intel Processor Frequency ID Utility was developed by Intel Corporation to
identify characteristics of the processor inside a system assuring the processor
is operating at the tested and rated frequency intended by Intel Corporation.
This ensures your processor is exactly what you ordered and not an overclocked