Sparkle Calibre X680 Captain Review

Nvidia’s GTX680 uses a system of ‘dynamic’ overclocking, otherwise known as ‘Boost clocks’.

This Boost clock mode uses a variety of factors to determine whether it is a good idea to run at higher speeds, or not as the case may be. It analyses power consumption, GPU load, temperature and memory load, among other factors.

The driver is coded to make on the fly decisions about what clock speed is safe in comparison with heat output and power use. The automatic overclocking algorithms need to be coded with a variety of safety parameters.

Above, the Sparkle Calibre X680 Captain. We can see that the boost speed is set to 1,189mhz (from a default of 1,059mhz). This is the ‘average’ clock speed that the core will run under during typical gaming load. The clock speed may actually exceed this speed depending on the given situation.

For overclocking today we used MSI’s Afterburner software. We spent a long time playing with the card and analysing how far we could push it without encountering instability.

Our sample of the Sparkle Calibre X680 Captain was supplied pretty close to the limit, with only 50mhz available on the core. This is a good enough safety margin long term. Our final overclock percentages were only 4.4% on the core and 3% from the GDDR5 memory.

The minor overclock translated to around 200 points extra in 3dmark 11, from 10,605 points to 10,887 points. Not really noticeable in the real world.

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