A graphic card or GPU is a computer component responsible for providing graphical output. Onboard graphics or IGP is found in motherboards except for high end boards. These days graphic chip is embedded inside the CPU die itself. These IGPs are just enough for basic usages like browsing, office applications and even HD video playing. But anything more than this requires a discrete graphic card which has more power to handle demanding applications like gaming.
Just like CPUs, GPUs have clock frequencies. They are CPU core (both ATI/AMD and Nvidia), shader (in Nvidia cards), and memory frequencies. By increasing the clock rate, one can improve the card’s performance.
Overclocking through BIOS
Just like CPUs, video cards can be overclocked through BIOS and software. Though BIOS overclocking is considered reliable for CPUs, it is not the case with GPUs. Though modifying the GPU’s BIOS with tools like Nibitor is possible to achieve overclock, lots of risks are associated with it. Flashing the GPU, in most of the situations, makes it unstable and can even brick the GPU and render useless when voltage values are changed. For these reasons, I’ll stay away from explaining BIOS overclocking for GPU.
Software overclocking your GPU
This is the most reliable way of overclocking your graphic card. There are many tools available to overclock a graphic card like Rivatuner, Afterburner, ATITool etc. But I have found MSI Afterburner, based on the venerable Rivatuner to be the easiest and most intuitive.
Once installed, you can see separate sliders for increasing the core voltage, core clock, shader clock, memory clock and fan speed. For both ATI/AMD and Nvidia cards, you may want to increase the core clock in 10MHz increments. For each increment check for stability with MSI Kombuster or Furmark for 10 minutes. Please note that the load created be these applications is far more than any real world application or game ever can and that leads to huge amount of heat produced. Make sure you provide enough cooling to your system case. Employing an aftermarket cooler can both keep the temperatures down and improve the chance of higher overclock.
Once you have reached the point where it is impossible to go beyond, reduce 10MHz and run the stress test for two hours. If the card is stable, you have found the max overclock you can achieve with your card. If it is not stable reduce 10MHz and run the stability test again. Do it until you reach the absolute stability.
If you have an Nvidia card, you should also overclock the Shader Clock. Select Reset in afterburner to reset the Core Clock to factory defaults and move the Shader Clock slider in Afterburner in 10MHz increments and follow the procedure explained above. Once you find the stable frequency, set your max Shader and Core frequencies and check for stability. If not stable, reduce in 10MHz increments the shader clock and/or core clock until the GPU is stable.
Overclocking the graphics memory
Just like core and shader clocks, you can overclock the memory to. Select Reset in Afterburner and simply move the slider Memory Clock and do the same procedure to find maximum stable memory overclock. Once done, set all values – core, shader and memory clocks to the values you just found and do the stress test again. If the card is not stable, you may want to reduce the memory, core or shader clocks to get a stable overclock.
If you want to see if there is any difference in performance overclocking, you can check that with 3D benchmarking applications like trial versions 3Dmark ’06 or 3D Mark Vantage. You can also download and install FRAPS, an application to show the frames rendered per second in a game to see the difference in gaming performance.
Please note that overclocking increases power consumption and heat produced. Always employ better cooling before overclocking. Also, make sure your power supply (PSU) can handle the increased load. Substandard PSUs may blow off taking other components along with it. Then comes warranty issue. Most of the graphic card vendors don’t provide warranty if your card gets damaged due to overclocking. The good news is that the chances of bricking your card are very less. Please note that I have not discussed anything about the Core Voltage tweaking as most of the cards don’t support voltage tweaking. Even if your card supports that, do make sure you don’t overvolt your card too much.