Clock Speed
When overclocking a component of your computer, the goal is to gain performance by increasing what is known as the clock speed. The clock speed of an Intel processor is the value that is most emphasized in advertising. For instance, the processor I bought was advertised as follows: “Intel Pentium 4 3.0GHz”. 3.0GHz!?!? Wow, that's a big number! What 3.0GHz means is that the processor is operating at 3 billion (3.0x10^9) cycles per second. After overclocking, we could be looking at somewhere around 3.5GHz, a pretty nice increase. However, with increased clock speed comes increased heat output, which is the primary enemy of overclockers everywhere.

Clock speed is actually the product of two values: the Front Side Bus (FSB) and multiplier. The FSB, to put it simply, is the path through which the CPU communicates with the rest of the computer. The CPU gets information from the RAM through the FSB, so the faster the FSB, the less time it takes for such an exchange to take place. In addition, the FSB of your RAM and the FSB of your processor allow your computer to function most efficiently when they are EQUAL. This is why it is just as important to maintain a synchronized RAM FSB clock when you are overclocking your CPU, as high discrepancies between the two can lead to your computer either not booting into the operating system, or not being very stable at all once it has booted. Intel processors, or at least the ones most of you probably have, have effective FSB speeds of either 533MHz or 800MHz. But of course this is also not that simple, silly Intel managed confuse us yet again. Current Intel processors are able to send 4 instructions per cycle on the Front Side Bus. You may have heard the term “quad-pumped” before, this is the term used to describe these Intel processors that boost their effective FSB by a factor of 4 by sending 4 instructions per clock. So this tells us that since the effective FSB speed is 800MHz, and that number was obtained by multiplying the actual FSB speed by 4, the actual FSB speed must equal 200MHz. This is the golden value of overclocking: the real FSB speed. The FSB speed of the processor, in our case 200MHz, is then multiplied by the multiplier to obtain the clock speed of the processor. The multiplier of my processor is 15. So:

FSB (200MHz) x Multiplier (15) = Clock Speed (3.00GHz)

As mentioned earlier, the FSB of the CPU and the RAM should be ideally equal. In the case of our 200MHz FSB CPU, we should want to have DDR400 (PC3200, 400MHz effective due to DUAL Data Rate (200MHz * 2), 200MHz clock speed) RAM. That seems relatively simple, but in reality it is actually more complicated than that. RAM is made using all sorts of different manufacturing processes and materials from several different companies. These companies label their RAM types as weird names, like TCCD, TCC5, CH-5, BH-5, and a whole lot of others. Well it turns out that certain types of RAM are A LOT better for overclocking purposes than other types of RAM, exactly which types are desirable will be mentioned later.