Overclock Your Videocard

Posted 02/26/2008 at 10:59am | by Michael Brown

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Overclocking an Nvidia Videocard

Step One: Set Fan Speed

In RivaTuner, click the Customize button in the Target Adapter box and then click the videocard icon to open a dialog box labeled “Low-level system tweaks.” Click the box labeled “Enable low-level fan control.” Take the software’s advice to reboot at this time, so it can detect the fan’s default state. Relaunch RivaTuner after the system restarts.

We want to see how far we can push the GPU, so we need to keep it as cool as possible. To do that, click Fixed. Now push the slider all the way to the right (to 100 percent) and click Apply. If the noise bothers you, set the fan speed to a lower value (but realize that you won’t be able to push your card as far when using a lower fan speed). If you can tolerate the fan at 100 percent, place a check mark next to the box labeled “Apply fan settings at Windows startup” and click Save. Place a check mark next to the box labeled “Restore fan settings after suspended mode” and click OK.

Step Two: Adjust Core Clock Speed

Now, click the Customize button in the Driver Settings box and then click the videocard icon. Click the box labeled “Enable driver-level hardware overclocking.” Here again, take the software’s advice and reboot so that it can detect the default memory and core clock speeds. Relaunch RivaTuner after the system restarts.

Return to the Driver Settings window in the main RivaTuner dialog box. Click the Customize button and then the videocard icon to open the System Tweaks dialog box. Place a check mark in the box labeled “Enable driver-level hardware overclocking” and select Performance 3D from the drop-down menu. Nvidia clocks its shader processors independently of the GPU’s core. RivaTuner defaults to linking the two components together, so increasing the speed of the core automatically and relatively overclocks the shader processors. We’ll leave them linked for this tutorial, but if you’re feeling saucy, experiment by unlinking the two by removing the check mark next to Link Clocks.

Now, use the Core Clock slider to begin probing the limits of your GPU’s core. If the core is stock-clocked, start with gross adjustments—say, 25MHz at a time (note: The arrow keys enable more precision than the mouse). Use a smaller increment if the card is already overclocked or if your system becomes unstable immediately. The idea is to find the system’s outer limit; once you’ve done that, back down in 5MHz increments until the system appears stable. Once you’ve achieved that, place a check mark in the box labeled “Apply overclocking at Windows startup,” and click the OK button

Before moving on to overclock the memory, stress-test the system with a benchmark that can run unattended for at least one hour. We use the two Shader Model 3.0 tests from Futuremark’s 3DMark06 because they can repeated up to 99 times.

The free version of 3DMark06 doesn’t run these benchmarks, but two other widely used stress tests are available for free: Nvidia’s GeoForms and Masaki Kawase’s Rthdribl.

Step Three: Adjust Memory Clock Speed

This step is identical to Step 2, except you’ll now be adjusting the Memory Clock slider. You’ll also want to bump your clock in smaller increments this time—say, 5MHz to 10MHz a whack. A warning icon in the form of a yellow triangle with an exclamation point will appear if RivaTuner thinks you’re getting too aggressive, but this isn’t necessarily a sign that you’re going too far; you won’t know that until you stress-test the system.

If the system seems stable, place a check mark next to “Apply overclocking at Windows startup,” click Save, and then click OK. Repeat your stress test for at least one hour. If you run into stability problems after adjusting the core, shader, or memory clock speeds, reopen the System Tweaks dialog box, click the Overclocking tab, and click the Default button to reset the card to its original values.

Final Thoughts: Know your Videocard's Warranty