The Video Card
The video card, the easiest part to overclock by far, serves as a nice introduction into the world of overclocking for those wishing to learn with the least amount of risk possible. Rather recently, both AMD and Nvidia have provided easy to use overclocking tools that can be used from within Windows, allowing easy overclocking of the video card(s) as well as introductory interfacing with the CPU, FSB and RAM. It is important to know that these programs are not the ideal way to overclock anything other than the video card, as they will not set system frequencies and timings until after Windows has fully booted, rather than as soon as the machine turns on.
Once in either of these utilities, overclocking is incredibly simple. Depending on the card, there can be up to three options: the Core Clock, Memory Clock and the Shader Clock. Generally speaking, the order in which to overclock will be:
1) Core Clock 2) Memory Clock 3) Shader Clock
If the BIOS is used in conjunction with these utility programs, it is also possible to increase the frequencies at which individual PCI Express slots run, as well as their individual voltages. If this option is used, treat it exactly the same as overclocking the CPU: increased frequency leads to better communication speeds between the graphics card and CPU, while increased voltage will both increase the stability of the graphics card and allow for greater frequencies.