ATITool 0.27

ATITool can be used to overclock any ATi graphics card.
Overclocking is the process where you run your hardware (like the Processor, Graphics Processor or Memory) in a speed which is not a standard speed it usually runs on. Generally, many graphics card manufacturer and 3rd party manufaturers, like those using the graphics chip to sell under their own brands, include facilities (softwares or hardware) so that we can overclock it.
One thing, overclocking your graphics card voids any warranty and can damage your hardware ( and it will be clearly stated while starting these programs) .

Now, ATITool is not created by ATi or AMD. But it can be used to overclock an ATi graphics card. The main feature is that it is compatible with any ATi graphics card. The program is really small and easy to use. It uses a driver to control the graphics card's clock speed. The program gives two sliders, one for GPU and the other for Graphics Memory. We can control the clock speed by that and only after we click "Set Clock", will the program overclocks.
We can also underclock! Just select a lower clock speed than that reported as the default speed.

There is a small 3D view window, which shows a small hairy cube rotating. It is rendered using the graphics card. It gives info about the frame rate.

We can make the program find the maximum clock speed where the card runs without any problem. What it does is that it increases the overclocing gradually till the hardware hangs. On restarting, we can view the log file to decide which overclocking configuration is good for your hardware.

Overclocking has the major problem overheating. So, make sure you have proper ventilation / cooling system for your motherboard and graphics card. Also, a powerful SMPS. You will also lose money on the electric bills!

Overclocking damages the graphics card or reduces its life. I wouldn't do that for gaming; only for testing.