Overclocking

The overclocking results listed in this section were achieved with the default fan and voltage settings as defined in the VGA BIOS. Please note that every single sample overclocks differently, which is why our results here can only serve as a guideline for what you can expect from your card.



The maximum stable clocks of our card are 1220 MHz core (11% overclock) and 1810 MHz memory (8% overclock).

I have to admit I'm impressed by the card's pretty good overclocking potential - for a card of this class. Dual GPU cards normally do not overclock as well as their single-GPU counterparts, but the low temperatures achieved through watercooling seem to help.

Overclocked Performance

Using these clock frequencies, we ran a quick test of Battlefield 3 to evaluate the gains from overclocking.


Actual 3D performance gained from overclocking is 9.4%.

Voltage Tuning

It has been a long known fact that overclocking headroom increases as soon as you increase the operating voltage. Software voltage control on VGA cards has, until recently, been the exception and most users were not willing to risk their warranty by performing a soldering voltmod. Almost all current graphics cards have voltage control in order to lower power consumption by throttling voltage during idle and slight load.

In this section, we will increase the GPU operating voltage step by step, and record the maximum clock speed possible. Voltage is listed as the value that the voltage regulator reports through software, not actual measured voltage. The card was installed into a case with fan settings at default. Memory will not be overclocked. We will, with a card that has thermal throttling, reduce the operating frequency to keep performance as high as possible for a given voltage. Please note that the fan profile will have an effect on observed temperatures: if the card gets hotter, the fan will ramp up to reduce temperatures or keep them from rising too fast.

The following graph shows the overclocking potential we saw on our sample. GPU clock is represented by the blue line, which uses the vertical clock scale on the left. The scale starts at the default clock to give a feel for the card's overclocking potential over its base clock. Temperature is plotted in red using the °C scale on the right side of the graph. An additional graph shows full system power draw in orange, measured at the wall socket while running at the given voltage, clock, and temperature.



Adding additional voltage did not yield that much of an improvement. Beyond a certain voltage, 1.35 V in our case, the card actually stopped gaining maximum frequency, going back down a bit.

Please also observe how quickly system power consumption ramps up and with it the GPU/water temperature.

Nevertheless, what we see is already a very respectable result. I'm sure the card will deliver higher numbers in the hands of more capable overclockers using extreme cooling.