Gigabyte HD 7970 Super OC 3 GB Review 52

Gigabyte HD 7970 Super OC 3 GB Review

Temperatures & Clock Profiles »

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, that's why our results here can only serve as a guideline for what you can expect from your card.



Maximum stable clocks of our card are 1155 MHz core (7% overclock) and 1905 MHz Memory (39% overclock).

The Gigabyte HD 7970 Super OC overclocks well, reaching higher GPU clocks than other HD 7970s we tested before. Memory overclocking potential is really outstanding and seems to benefit a lot from the adjusted cooling design which seems to provide better airflow to the memory chips.

Maximum Overclock Comparison
Max. GPU ClockMax. Memory Clock
Gigabyte HD 7970 SOC1155 MHz1905 MHz
MSI HD 7970 Lightning1210 MHz1850 MHz
VTX3D HD 79701100 MHz1750 MHz
AMD HD 79701075 MHz1715 MHz
AMD HD 7970 GHz Ed.1185 MHz1635 MHz
Important: Each GPU (including each GPU of the same make and model)
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 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 9.7%.

Voltage Tuning

It has been a long known fact that overclocking headroom increases as soon as you increase the operating voltage. Until recently, software voltage control on VGA cards has been the exception and most users were not willing to risk their warranty by performing a soldering voltmod. Nowadays almost all current graphics cards have voltage control in order to achieve low power consumption by lowering voltage when in idle or slightly loaded.
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 via software, not actual measured voltage. The card was installed in-case, with fan settings at default, memory will not be overclocked either. If a card has thermal throttling we will 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 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 overclocking potential over the 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 when running at the given voltage, clock & temperature.



Gains from voltage are decent, but I expected a bit better. The card could not beat 1200 MHz, even with a scorching 1.4 V. At that point the five little fans were spinning like crazy, running over 8000 RPM, making a lot of noise. However, we our graph suggests that the card has more potential in it as there is no sudden clock drop off beyond a certain voltage.
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