Overclocking

After our fantastic experience with the stock GTX 275, which we were able to overclock all the way up to monster clock speeds of 745MHz core, 1,652MHz Shader and 1,404MHz (2,808MHz effective) memory, we were really hopeful that the Palit card’s custom cooler would allow us to match, and perhaps even better these heights.

Unfortunately, we were very disappointed with the overclocking potential on show in our review sample. Any increases in the card’s memory clock lead to immediate instabilities and increasing the core and shader clocks to 700MHz/1,560MHz, while initially stable, failed our long term overclocking stress test and started to display worrying signs of artifacting.

Also of concern was the card’s increased operating temperatures, which when under heavy load for long enough eventually topped 90°C and immediately caused a driver error, crashing the stress test before the card’s firmware could spin up the cooling fans above their stealthy 30 percent speed.

We think it's the card's custom cooler that's to blame for the stubborn memory clock speed - the memory is cooled by the large thin aluminium heatsink rather than the heat pipe cooler used to cool the GPU itself. As the memory is only being cooled by second hand airflow flowing through the GPU's heatsink it obviously just can't handle any sort of overclock, unlike the large heatsink on the stock card which cools all the card's components using one combined cooler.



Eventually we found the safest reliable overclock to be 680MHz on the core, 1,508MHz on the shader and the unchanged 1,134MHz (2,268MHz effective) on the memory: a disappointing improvement of just seven percent and a long way off what we achieved with the stock GTX 275 we looked at a few weeks ago. This minor overclock led to increases in Crysis performance of around 1.5FPS on the average framerate and 1FPS on the minimum frame rate - hardly noteworthy.

It’s a real shame considering the extra cooling on offer from the improved dual fan cooler, but it is important to remember that with overclocking of any kind, your mileage may vary, and just because our card failed to overclock well, doesn’t mean all of them will.

Still, the fact that the graphics driver crashed due to the high GPU temperature without the cooling fans spinning up is a genuine concern. We suspect that Palit has used the GTX 275’s stock firmware, which only increases fan speed when the card reaches 90°C, but that’s no use if Palit’s model starts throwing out driver errors and artefacts before it ever reaches that temperature, overclocked or otherwise.