Introduction:
The science behind how to produce a thermo-nuclear device is public knowledge, but would you build one? It's a
rhetorical question, but you get the point. The same thing applies to overclocking. A little knowledge is a dangerous
thing. There are risks involved in overclocking, and if you are not prepared to accept those risks (i.e. damaging your
motherboard, processor, or other components) then overclocking is not for you. That being said, this series of
articles will introduce you to the basic principles of overclocking, the equipment used, and the techniques involved
in squeezing every last ounce of performance out of your microprocessor.
NOTE: The information being provided in this article is for information purposes only. The author and the
MODTHEBOX.com website are not liable for any damage to person or property caused by attempting to modify any device
beyond the manufacturer's specified design.
Webopedia defines overclocking as "To run a microprocessor faster than the speed for which it has been tested and
approved." You will notice the use of the word microprocessor. Overclocking is not exclusive to CPU's. Video cards
have a GPU, or graphics processing unit, which can be overclocked for additional performance. While video card
overclocking will be touched on in this series of articles, the majority of the content will focus on overclocking
Intel and AMD processors.
Before continuing, there is a glossary of terms and acronyms that will be used in this and other articles you should
understand. Definitions of theses terms or acronyms will be provided as they are introduced:
FSB: Front side bus
The front side bus is the main method for every component on your motherboard to communicate with the processor. The
faster the front side bus, the faster your computer can process a given task. In modern motherboards, standard front
side bus speeds are 100 or 133 MHz.
Multiplier:
A factor applied to the front side bus to derive the CPU speed. For example, an Intel Pentium III 900 processor running
on a standard 100 MHz front side bus would have to be using a 9x multiplier (9X100=900MHz). Older systems referred to
this scenario as the internal and external clock speeds. Internal to the CPU, operations happen at 900 megahertz, but
outside the processor, or externally, timing is set to 100 MHz.
Basic overclocking:
There are two primary ways to overclock an AMD or Intel microprocessor. One is to increase the multiplier for the CPU,
and the other is to increase the FSB on the motherboard. By increasing the multiplier, you are effectively overriding
the design specifications for the CPU by forcing it to run at a higher frequency than the manufacturer recommends.
Modifying the speed of the FSB increases the speed at which the motherboard communicates with the CPU.
Adjusting the FSB:
By adjusting the value of the front side bus, you are modifying the base speed at which the CPU operates. By default,
most processors run at 100 or 133 MHz. Depending on the limitations of your motherboard, you may be able to increase
the FSB to 150MHz or beyond. On a CPU that runs at 100 MHz, like a 1 GHz Intel Pentium 3, adjusting the FSB to 150
will effectively increase the speed of the CPU by 50% (10X multiplier X 150 FSB = 1500 MHz or 1.5 GHz). Sounds easy,
but it gets a little more complicated than that. The problem is twofold:
- Some motherboards simply cannot operate at extremely high front side bus settings. There are physical limitations
to how well the traces can transfer signals from one component to the next without degradation.
- The FSB is not dedicated for CPU usage. Memory, AGP and PCI slots all use the FSB as well to communicate with
the CPU. So even if you’re CPU and motherboard can handle the increased FSB setting, other components in your system
could keep the system from being overclocked with high FSB settings
The actual process of overclocking a machine by increasing the FSB is relatively painless. The only prerequisite is
that your motherboard must support manual CPU speed settings. If you have a jumperless board, this is a simple
process, go into your BIOS, set your CPU Speed to manual, and increase the FSB setting. Some motherboards will only
allow the CPU to be set using jumpers. Check your user manual for the available configurations.
The best way to find out the highest FSB speed your system will support is through burn-in testing. Adjust your FSB
to the desired overclock level and try to get the system to POST and launch the operating system. If either the
operating system or the POST do not complete, lower your FSB until you can get successfully past these two hurdles.
(Other adjustments can be made if you cannot POST or launch the OS, but they will be discussed in a future article.)
This may require resetting your CMOS, but on most boards, if the board is unable to successfully POST, it will revert
back to default values. Once the operating system does load, don't think your job is over. You need to test for
stability. Loading the OS requires very little effort on the part of the CPU and other components, so you need to
run a burn-in test to tax all the components of your system for a lengthy period of time to determine if the system
can SUSTAIN the new overclocked settings. If your system passes all the burn-in tests, it is a good bet that the
system will support the new settings. However, your day-to-day operations will truly determine if the overclock has
been successful. Program errors, flickering images on screen and such can be the results of the new overclock
adjustments, monitor the symptoms and scale back the overclock if it becomes persistent.
