Overclocking

The overclocks 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.



HD 7870 (1st picture): Maximum stable clocks of the card are 1205 MHz core (21% overclock) and 1520 MHz Memory (27% overclock).

Outstanding results! 1205 MHz GPU clock is actually the highest clock we have seen on any graphics card tested so far. Memory overclock well, too, to the typical levels for these chips.

The HD 7850 overclocks a bit worse than the HD 7870 in terms of maximum clock speed, but that is to be expected from a lower-grade GPU. Maximum clocks are 1140 MHz (+33%) and 1580 MHz (+32%).

Overclocked Performance

Using these clock frequencies we ran a quick test of Call of Duty 4 to evaluate the gains from overclocking.


Actual 3D performance gained from overclocking is 18.7% (HD 7850) and 18.5% (HD 7870).

Temperatures

Temperatures are low, I would have preferred less noise for slightly higher temperatures.

Clock Profiles

Modern graphics cards have several clock profiles that are selected to balance power draw and performance requirements.
The following table lists the clock settings for important performance scenarios and the GPU voltage that we measured. We measure on the pins of a coil or capacitor near the GPU voltage regulator.

HD 7870

HD 7850