As you are now aware, overclocking your graphics card can be a quick and easy way to squeeze a bit more performance out of your system without having to spend any more money. In this case we were able to push the GeForce 8600 GT, which costs around $135 US, to rival the more expensive GeForce 8600 GTS graphics cards, which cost roughly $190 US. The advantage to doing this with an 8600 GT graphics card is that it can be powered for a basic 300-400w power supply and there are no additional PCI Express power cables required.
Read on at Legion Hardware.