OverclockingThe 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 1230 MHz core (12% overclock) and 1790 MHz memory (8% overclock).
GPU overclocking ends up higher than any other HD 7970 we tested, except for the Sapphire HD 7970 Toxic. Memory overclocks well too, but doesn't quite reach the levels we have seen on other cards.
Important: Each GPU (including each GPU of the same make and model)
|Maximum Overclock Comparison|
|Max. GPU Clock||Max. Memory Clock|
|ASUS HD 7970 Matrix||1230 MHz||1790 MHz|
|MSI HD 7970 Lightning||1210 MHz||1850 MHz|
|GIGABYTE HD 7970 SOC||1155 MHz||1905 MHz|
|PowerColor HD 7990 Devil 13||1085 MHz||1740 MHz|
|Sapphire HD 7970 Toxic||1275 MHz||1885 MHz|
|AMD HD 7970 GHz||1185 MHz||1635 MHz|
|AMD HD 7970||1075 MHz||1715 MHz|
will overclock slightly differently based on random production variances.
This table just serves to provide a list of typical overclocks for similar cards,
determined during TPU review.
Overclocked PerformanceUsing these clock frequencies, we ran a quick test of Battlefield 3 to evaluate the gains from overclocking.
Actual 3D performance gained from overclocking is 10.6%.
Voltage TuningIt 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.
I could not find any gains due to increased voltage, which is very surprising. There was absolutely no improvement in clock stability, but voltages, power, and temperatures went up, proving the voltage was applied. I verified this with physical measurements.
Nevertheless, 1240 MHz at stock voltage 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.