Overclocking The Graphics Memory

Let's start by overclocking the first GPU's memory clock, as it is selected by default. Overclock it in small steps. On our testbed, each scroll step on the mouse increased the memory clock speed by 14 MHz, so we overclocked by 14 MHz steps. After selecting the new memory clock speed, click Apply. Then test it out using a real 3D game like Crysis or Far Cry 2.

When you test the overclocked card, be sure to note any visual abnormalities like corrupted textures. The game may even hang. This is a sign that one or more of the memory chips is failing at that clock speed. When that happens, reduce the memory clock by one step. If the game runs well, increase the memory clock by another step. Keep doing this until you discover the highest clock speed where the GPU#1's memory chips are stable.

Remember, the GeForce GTX 295 is essentially made up of two cards, each with its own GPU and memory chips. After you are done overclocking the memory chips of GPU#1, be sure to reset it to the default clock speed. Then select GeForce GTX 295 - #2 so you can overclock the memory chips of the GPU#2.

It is important to first reset the memory clock of GPU#1 so that it does not affect the overclock of GPU#2's memory clock. Follow the same steps as you did earlier for the memory clock of GPU#1 until you discover the highest clock speed where the memory chips are stable.

Once you know the maximum stable clock speeds for the memory chips of both GPU#1 and GPU#2, it's time to test them together. Set the memory clock speeds for both GPU#1 and GPU#2 to their maximum stable clock speeds and test them using a 3D game like Crysis or Far Cry 2.

Again, look for any visual abnormalities, and increase or decrease one or both of the memory clocks as necessary. Unless you are really rabid about maximizing the clock speeds of the memory chips, it would be easier to just adjust both memory clocks at the same time. Thanks to the earlier separate overclocking trials, you will be able to quickly find the maximum stable memory clock speeds for both GPU#1 and GPU#2.

Once you are satisfied, you can further reduce the memory clock speeds for both GPUs by one step for added stability (in case of temperature or voltage changes). Otherwise, it's time to overclock the GPUs!

Overclocking The GPU

First, restore the memory clocks of GPU#1 and GPU#2 to their default clock speeds. Then repeat the same steps as above for the GPU#1. On our testbed, each scroll step on the mouse increased the GPU clock speed by 20 MHz, and the shader clock by 43 MHz. Although you can overclock the core and shader clocks separately, we chose to overclock both in sync - raising both by one scroll step each time.

After you have selected the core and shader clock speeds you want for GPU#1, click on the Apply button and test the card using a real 3D game. Again, look for visual abnormalities in the game. Sometimes, the game may stall with the monitor blanking out for a moment. This is a sign that the GPU is running too hot and the graphics driver is attempting to recover. Usually, it succeeds and the game resumes. When this happens, clock down the core and shader clocks.

If the game runs well, increase the core and shader clocks by another step. Keep doing this until you discover the highest clock speeds at which the GT200 GPU is stable. Then it's time to overclock the second GT200 GPU. Before you do that though, be sure to reset the core and shader clock speeds of GPU#1. Then select GPU#2 and repeat the steps until you discover the maximum stable clock speed of GPU#2 as well.

Once you know the maximum stable clock speeds of the two GPUs, it's time to test them together. The increased thermal output of the two overclocked GPUs will likely result in lower stable clock speeds when both GPUs are overclocked simultaneously. So, set both GPU#1 and GPU#2 to their maximum stable core and shader clock speeds and test them out using a 3D game like Crysis or Far Cry 2.

Again, look for any visual abnormalities, and increase or decrease one or both of the GPU clocks as necessary. Unless you are really rabid about maximizing the clock speeds of the GPUs, it would be easier to just adjust the core and shader clocks of both GPUs at the same time. Thanks to the earlier separate overclocking trials, you will be able to quickly find the maximum stable core and shader clock speeds for both GPU#1 and GPU#2.

Once you are satisfied, you can further reduce the core and shader clock speeds for both GPUs by one step for added stability (in case of temperature or voltage changes).

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