It may have been the low-quality of our GPU or just bad luck, but the overclocking potential of our sample of the card turned out to be mediocre. We could only overclock the GPU to 1180 MHz without increasing its voltage.
The memory chips weren’t prone to overclocking, either. We reached a memory frequency of 6680 MHz only. Thus, the resulting clock rates were 1180 MHz (+12.4%) and 6680 (+11.3%) for the GPU and memory, respectively.
The temperature of the overclocked card didn’t change much in the automatic fan regulation mode:
We were not satisfied with such results, of course. So, we put in our earplugs, set the fan to its maximum speed and increased the GPU voltage to 1.3 volts. We then notched a more rewarding result of 1250 MHz:
Here’s the temperature of the overclocked card with increased voltage:
The peak GPU temperature is 77°C (at the cooler’s maximum 5400 RPM). Hopefully, off-the-shelf GHz Edition cards will be equipped with better coolers in terms of both noisiness and efficiency.
We measured the power consumption of our testbed equipped with different graphics cards using a multifunctional Zalman ZM-MFC3 panel, which can report how much power a computer (without the monitor) draws from a wall outlet. There were two test modes: 2D (editing documents in Microsoft Word or web surfing) and 3D (three runs of Metro 2033: The Last Refuge benchmark in 2560x1440 resolution with maximum image quality settings).
Here are the results:
It’s clear that our testbed with an overclocked six-core CPU is going to be satisfied with a 550-watt power supply irrespective of which of these graphics cards we install. The new Radeon HD 7970 GHz Edition needs 20 watts more than the ordinary Radeon HD 7970 and about 80 watts more than the non-overclocked GeForce GTX 680. We can also note that the peak power consumption of the systems doesn’t grow up much when the graphics cards are overclocked, even with an increase in GPU voltage. The systems are all comparable in terms of their idle power draw.