Overview
Here's a basic outline of the kind of stuff you will find in
this guide.

- Necessary tools
- Safety precautions
- Bus Clock Speed
- Bus Clock Multipliers and Multiplier Locks
- Chip Voltage and Stability
- Cooling!
- The Overclocking Process
- Stability Testing Procedures
- Troubleshooting a Failed Overclock
- Electrostatic Migration and Burnout
- Overclocked Processor Lifetime
- Effect of Non-standard Bus Speeds on Other Computer
Components
- Alternative Methods of Overclocking

Necessary Tools

There are several things you need to know before you begin
trying to overclock a computer. Depending on the part of the
computer you are trying to overclock and how far you are
going to take the process, you may need any or all of the
following things:

- Phillips head screwdriver
- Flat head screwdriver
- Tweezers
- Thermal Paste
- Thermal Tape (FragTape)
- A flat razor
- Cooling fan/Peltier/etc.
- Application Specific Tools (ex: Peltier cooling systems
may require insulation)

Make sure you have ALL the tools you need before you begin
working (in some cases, you may not need any tools at all).
Make sure you are in a clean, well-ventilated area, with
plenty of workroom (if you will be taking on a larger
project).

Safety Precautions

There are a couple of very important things to keep in mind
when you are attempting to overclock a computer, so that you
don't damage your equipment. The first of these things is to
make sure you have adequate cooling to take on the project
you are planning. As will be discussed later, cooling can
make or break an overclock - but that isn't its only
benefit. It also helps prevent damage being done to the
chips due to excessive heat.

Ok, now that I have taken care of explaining the importance
of cooling to you, on to the (second) most important safety
precaution - which has to do with progressive overclocking.
I know, I know, that isn't a term most people have ever
heard of - and that's because I just coined the term.
Progressive overclocking has to do with the process of
slowly clocking your system faster and faster until it
reaches its peak stable speed. This is frequently done with
video card overclocks, because it is very easy to over do it
and fry the card. The process with video cards is very easy -
you simply overclock in 5 MHz increments until you reach an
unstable speed, and then downclock the card in 1 MHz
increments until you reach a stable speed. Then of course
comes the obligatory testing to determine whether or not the
card is stable even during system strain - and if it passes,
you're gold.
However, the process with a CPU is more difficult - mainly
because it is hastlesome to go back into the BIOS for every
clock change. With bus clocks, bus multipliers, and chip
voltages to contend with, things aren't always hunky-dory.

Bus Clock Speeds

The system bus clock is a very important concept when
dealing with system overclocking, particularly when you are
dealing with an Intel-based system. This is because Intel's
processors are multiplier locked. More on that subject
later, however. Right now I want to explain to you about the
system bus and how it can effect your system.

The bus clock I am referring to is the system bus on which
the processor communicates with the rest of the computer. It
is derived directly from the computer's internal quartz
crystal which runs at ~12 MHz (and subsequently also runs
the computer's internal clock). This bus speed, when taken
into account with the processor's bus multiplier, determines
what speed the CPU runs at, as well as some other things.
You see, the PCI and AGP slots derive their bus speeds from
the system clock (33 and 66 MHz respectively) using a bus
divider. These dividers have been set up specifically for
the standard system bus speeds (66/100/133), but don't work
quite as well for the non-standard bus speeds. That means
that, unless you are jumping from 66 to 100 MHz, or from 100
to 133 MHz, you will also have to over or under clock your
system buses - and sometimes they don't take kindly to the
extra stress.

System Bus Multiplier and Multiplier Locks

The system bus multiplier takes the system bus * whatever
the multiplier is to determine the speed at which the
processor is running. That means that a computer running at
the 100 MHz bus speed with a 4.5 bus multiplier would be
running at 450 MHz. Simple enough to overclock your computer
without messing with the system bus, right? Wrong. Why is
that? It is because Intel had the audacity to lock the clock
multiplier on its processors. That means that your computer
HAS to use the 4.5 bus multiplier to derive the processor's
clock speed, and dramatically limits the speed range of most
processors. This, combined with the fact that most computer
components don't function properly on non-standard bus
speeds, makes overclocking most computers difficult (to get
a completely stable system you have to jump up to the next
standard bus speed - a mighty task for most processors).

Of course, AMD has (sort of) come to the rescue by not
locking the system multiplier. However, to change the
setting, you have to break the chip's casing open, hence
voiding the warranty (overclocking voids your warranty
anyway - so no big deal). They were even so nice as to
include an edge connector to allow the connection of third-
party jumpers to make overclocking a snap. Of course, you
get the best results using a soldering iron... but that's an
entirely different article.

Chip Voltage and Stability

Chip voltage can turn a not-quite-so-stable chip into rock
hard granite. Most CPU's have some sort of way to change the
voltage of the chip. Raising (and in some rare cases,
lowering) the chip's voltage can create a much stabler chip,
at the cost of more heat. Heat, of course, alternately
lowers the overclockability of a chip, but it doesn't lower
the chip's overclockability as much as upping the voltage
raises it. And besides, there is always cooling. But more on
that later.

The basic theory on chip voltage and how it affects the
processor is this: a higher chip voltage increases the
signal strength between transistors within the chip,
allowing the signal to ignore greater discrepancies within
the silicon core itself. You see, the silicon wafers used to
make the chips aren't always pure, and they definitely
aren't all of the same quality. A chip with a higher clock
rate is generally going to have a core made of a higher
quality silicon wafer (something that can't be determined
until after fabrication, due to the fact that all the wafers
are as pure as they can make them).

Now, the processor signal has two choices as to how to deal
with a chip impurity (how it is dealt with has to do with
quantum physics and really isn't imperative to this
discussion). It can either jump the gap, or go around it.
When the processor frequency is lower, the signal has the
time to go around the defect if need be, but if the
frequency is too high and the signal must go around, the
signal doesn't get to its destination in time or at all
(remember we are dealing with millionths or billionths of
seconds), causing a miscalculation that usually will cause
some form of software error (commonly it causes a crash).

However, upping the core voltage is like giving the signal a
running start, it allows the signal to jump gaps within the
chip with relative ease (sort of like a lightning arc), and
the signal gets to it's destination in time.

Cooling

Two of the parts of the overclocking process up the heat
produced by the processor - upping the frequency (the actual
overclock) and upping the core voltage. Excessive heat
within the core creates more of those gaps that I was
discussing above for the signal to cross, and too many of
these gaps will weaken the signal to the point where it
becomes non-existent and creates some more of those
wonderful software errors. Here's the lowdown for you
physically inclined folks - the extra heat energizes the
particles within the silicon wafer. The pathways within the
silicon wafer are approaching the size of light rays (read
very small), so if the particles move too much, they break
their connection with the other particles within the
pathway. These temporary breaks do the same thing as the
impurities mentioned above. Got it? Good.

Ok, now that you know all about why cooling is so important,
here's the skinny on what kind of stuff is available to you
hobbyist overclockers out there, and then maybe I'll do a
little of the honorable mention thing to the more expensive
cooling systems of the world. The simplest way to cool your
chip is called passive air-cooling. Passive air-cooling is
basically the use of the surrounding, cooler air to cool the
chip, using some sort of ball bearing fan. This is the
cheapest, easiest, and most common way to cool your
processor - all it entails is attaching a fan/heatsink combo
to the processor to cool the thing down.

Hard-core hobbyists, however, are never satisfied with
simple 'air' cooling, oh no. Heck, I've even seen some guys
go so far as immerse their systems into super-cooled
glycerin (a non-conductive liquid) to cool their processors.
But that, once again, is a subject for another article.
There are two 'reasonable' types of active chip cooling.
One, a Peltier system, basically uses a heat-transfer plate
(called a Peltier) to conduct heat away from the processor,
where it is then carried off by a standard fan/heatsink
combo. The only extra stuff you need for this type of system
is some form of insulation for the exposed portion of the
cold side of the Peltier, because otherwise you will get
condensation, and even frost (Peltiers are extremely
efficient).

The other 'standard' form of active cooling is using some
form of water cooling device. These devices are extremely
complex, and on top of the mandatory insulation, you also
need a pump and some form of condenser... for the average
hobbyist, it would be easier to put your computer in the
freezer and run the wires out through a self-drilled hole
rather than set one of these bad boys up.

Of course, you always have the "professionally" overclocked
systems from companies such as Kryotech. Kryotech uses a
method of cooling called "liquid phase change cooling." It
is extremely efficient but also extremely expensive - the
special case alone costs \\$1000 US all by itself, not
including the processor enclosure. Boy, what some people
will do for a couple of extra megahertz. Anyhow, if you've
got the cash, their systems are something you might want to
look into.

To install a cooling device, first you need to remove the
old fan/heatsink combo from your processor. This should be a
fairly simple operation. Don't be afraid to use a little
force to break the seal that was created by the thermal
compound. You will then need to use a flat razor to remove
the remainder of the thermal compound from the top of the
processor. Once this is complete, apply either some more
thermal compound or thermal tape (FragTape) to the top of
the processor and attach the new heatsink on top of that.
Simple enough, huh? Some setups may have other necessary
steps to attach the cooling device (thermally insulating
silicon caulking compound, etc.) to prevent condensation -
but that won't be a problem with a standard fan/heatsink
combo.

This guide only explains the very basics of overclocking, at
a later date I will add an article which explains it more
thoroughly.

The Guide