How do I Overclock my CPU?

Overclocking is the process making a computer component run at a higher speed than that specified by the manufacturer. The CPU is one of the components of the system that is commonly overclocked. The CPU clock speed is the product of the FSB (Front Side Bus) speed and the CPU's multiplier (sometimes called the clock ratio).

CPU Clock Speed = FSB Speed * CPU Multiplier

Thus the CPU clock speed may be increased by increasing either one or both of these factors. However it is interesting to note that increasing the FSB speed will a greater impact as it increases factors such as memory speed (for synchronous operation) as well as the processor speed. The CPU multiplier is also comparatively difficult to adjust.

The following section describes how overclocking may be done using the BIOS. Enter the BIOS during system startup. Select the Bios Features Setup, CPU Soft Menu or any other similar option and press Enter. Modify the CPU Host Bus Frequency, External Clock (PCI) or similar option shown with Page Down until you find the motherboard FSB speed you want (for example 200 MHz for processors whose FSB normally works at 166 MHz). In the CPU Core section find the Multiple Bus Frequency or Multiplier factor and modify the value of the CPU Multiplier (for example 11x may be changed to 13x). Now save the changes to the CMOS and exit. It is generally advisable to change the parameters in steps. For example increase the FSB speed by a few MHz and check whether the system boots. If your computer boots increase the speed further and check again. Repeat until you have the highest setting with which your computer will boot up. Now test your OS with some resource hungry application say a game, to check whether the system crashes. If it crashes lower the FSB speed in steps till the point where the system is stable.

Overclocking results in change to the voltage profile within the circuitry. This can be minimized by increasing the voltages applied but too much increase can burn up the circuitry. A bigger problem is the heat generated due to overclocking. This is tackled through the use better CPU heatsinks and fans, heat spreaders on memory, fans on video cards and case fans.