How to Overclock Your Graphics Card

Many PC gamers eagerly await the release of next-generation graphics cards, hoping that the new hardware will boost frame rates and enhance eye candy in the latest games. However, while a graphics card upgrade is almost always a good way to increase game performance or improve image quality, new cards tend to be expensive--and they aren’t always necessary.

Today, even midrange graphics cards are generally fast enough to pump out buttery-smooth frame rates in cutting-edge games at all but the highest resolutions. If your current graphics card is serving you well, and you’re just looking for a little something extra to increase performance, overclocking may be the better way to go. And it will certainly be more affordable.

Why Overclock?

In its early days, overclocking may have been a black art reserved for the most hard-core computer geeks, but nowadays it’s about as easy as can be, and it’s usually safe too. Yes, overclocking a component can shorten its life span. But if you don’t push things too far, and if you keep temperatures under control, you have little reason to worry.

You’ll want to make sure that your system has adequate cooling and a power supply that’s sufficient for handling an overclocked card. Modern graphics cards typically have thermally controlled fans that will spin faster to better dissipate heat from the overclocked board. The card may become somewhat noisy as a result, but if the overclock remains stable and the graphics card’s cooler can keep up, you should be good to go.

Both AMD and Nvidia (the big two graphics-card makers) have built overclocking tools into their drivers. AMD’s are readily available (on supported cards) in the AMD Overdrive tab, listed in the Performance section of the company’s Catalyst Control Center software suite. Nvidia’s overclocking tools aren’t exposed by default in its GeForce drivers, but installing its System Tools utility will make them available. You’ll need to grab the Systems Tools utility from the Nvidia website; once you've installed the utility, frequency controls will be visible in the performance and tuning section of the GeForce driver.

Disregarding software/driver optimizations, game engine tweaks, and system interface speeds, the performance of a graphics card is typically determined by the compute speed and fillrate of its graphics processing unit, as well as by the amount of memory bandwidth its frame buffer memory affords. (The amount of frame buffer memory on the card can also come into play as resolutions and texture sizes increase, but that’s a discussion for a different article.) By increasing the frequencies of the GPU and the frame buffer memory on your graphics card, you can make them process and move more data, more quickly, increasing overall performance.

How to Overclock ?

Overclocking a graphics card is a fairly straightforward process. All you need is a working and properly configured graphics card, and a few of your favorite games or a benchmark like Futuremark 3DMark 11 to test stability. For the purposes of this article, we used a brand-new AMD Radeon HD 7950 installed in a high-end, Intel-powered test rig running Windows 7 Ultimate (64-bit).
Before you begin overclocking, install the latest drivers for your graphics card (and Nvidia’s System Tools if necessary), and play a few games to ensure that the system is stable. If all is working well, restart the system, open the graphics card’s control panel, and navigate to the overclocking or frequency control section; we used the Overdrive tab built into AMD’s drivers.

First, enable Overdrive by ticking the necessary box, and max out the power control settings to eliminate any power-related frequency restrictions. Next, increase the GPU frequency by moving the appropriate slider by a few MHz at a time, and apply the settings. Then, play a game or loop a benchmark to test stability.

For example, our Radeon HD 7950’s GPU was clocked at 800MHz by default. We started by moving the GPU clock settings slider in 10MHz increments, until our test system became unstable. That is, once we encountered any visual anomalies, or a game or the system crashed, we turned the GPU frequency back down by 10MHz and tested for stability again. Ultimately we settled on a stable GPU frequency of 1000MHz--an increase of 200MHz over stock.

With our peak GPU frequency known, we set it back to its default clock speed and then focused on the graphics card’s memory. By default, the Radeon HD 7950’s memory is clocked at 1250MHz. We used the same procedure of increasing the memory frequency by 10MHz at a time, testing stability each step of the way. In the end we achieved a stable memory frequency of 1500MHz.

We recommend overclocking the GPU and memory individually to isolate any instability that the tweaks may introduce to that particular component. Once you know the peak frequency for both, set the GPU and memory to those speeds simultaneously and test for stability once more. If all is well, enjoy your newfound performance. If not, back the frequencies down a bit further for both, and test the graphics card again. I must also point out that some graphics cards may remain stable while overclocked, but offer lower performance when running at higher frequencies due to thermal or power throttling. If your system remains stable but the performance degrades while you're overclocking, reduce the GPU and memory frequencies until performance begins to scale properly.