First things first - overclocking does technically void your warranty. There's no sure-fire way of testing whether a component has ever been overclocked or not, but if you're particularly worried about this aspect then you should probably stop reading about now.

There is also the minute but real possibility that you could damage one or more of your components by overclocking. If you need reassurance then just head into any overclocker's forum on the planet and check how many people are complaining about their parts dying due to sensible overclocking - you'll find they are few and far between. Either way, taking the risk is solely your responsibility.

What is overclocking?

Overclocking, as the name suggests, is the art and science of running your PC components at clock speeds over their rated or marketed value to increase performance.

You may ask: why don't manufacturers just set their products to run at these faster speeds in the first place and sell them for higher prices to make more money?

There are a few answers to this. In a nutshell - all the chips coming off an assembly line are not created equal. Each chip will have a different amount of microscopic flaws which affect its tolerance for punishment. Manufacturers need to pick specifications which can be safely run by all the parts they are selling - it's no good advertising a 4GHz CPU if only 50% of the chips you're selling can actually run stably at that speed. Moreover, running things at faster speeds consumes more energy, and manufacturers like to stick to as low a power rating as possible.

The CPU (central processing unit) is the most common component to overclock so I will take you through the ins and outs of this part. Overclocking your CPU usually also involves overclocking your motherboard and RAM so we'll touch on these areas as well.

What you will need

The main thing you need is patience. There can be a lot of reading, adjusting, rebooting and testing involved, so don't expect to be able to twiddle a couple of settings and be done with it. This isn't a bad thing as most people learn a lot of new things about computers during this process.

The other more tangible thing you might need is good cooling. You can clock your CPU up a little bit with a stock cooler, but you will have a whole lot more headroom with a decent HSF (heatsink and fan) and much less chance of the dreaded thermal shutdown. Generally, I would recommend spending no less than $50 and no more than $150 on a decent HSF, so get the best your budget will allow. Thankfully, this is generally the only time you'll need to open your wallet to get a mild overclock.

There are also a couple of applications you will need to download, but we'll come to those shortly.

The fundamentals

To explain the basics, let's take the Intel Core 2 Duo E8500 as an example. This dual core CPU is rated at 3.16GHz (3166MHz), which is calculated by taking the speed of the FSB (front side bus, the part of your motherboard where data flows from the CPU to the rest of your system) and multiplying it by the CPU's multiplier. In this case, the E8500 operates on a 333MHz FSB and has a 9.5x multiplier. From this we can see that 333 x 9.5 = 3166 (approximately, these figures aren't always exact). Luckily that's about as hard as the mathematics will get.

(At this point I should mention that the new Core i5 and Core i7 Intel platforms no longer use a FSB - it's now called a QPI (Quick Path Interconnect), and AMD uses a HT (HyperTransport) link, but they're all effectively the same thing so I will stick to calling them all a "FSB" for simplicity.)

So if you want to run your CPU faster than its rated speed, it should be obvious that you have to do one of two things - either raise the FSB, or raise the CPU multiplier. Unless you have one of AMD's "Black Edition" CPUs or Intel's very expensive "Extreme Edition" CPUs, you won't have the option to raise the CPU multiplier, so increasing the FSB speed is the only way to overclock for most people.

Next page: Clock it up