It’s already no secret that the 28nm AMD Tahiti chip boasts high overclocking potential and so does the Tahiti-based Radeon HD 7970. In fact, AMD put an emphasis on this fact in the presentation:
Many graphics card makers have already announced pre-overclocked Radeon HD 7970s and their factory overclocking is as high as 125 to 150 MHz or even more!
As for our sample of the reference card, we used MSI Afterburner 2.2.0 Beta 10 to overclock its GPU from 925 to 1130 MHz (+22.2%) and its memory from 5500 to 7000 MHz (+27.3%):
The memory bandwidth reached an enormous 336 GB/s and the texture fillrate notched 144.6 GTexel/s! The overclocked card grew 5°C hotter in terms of its GPU temperature and its fan accelerated to 2990 RPM:
Of course, you’ll need at least more efficient air cooling (and we'll tell you about it in an upcoming review) or, better yet, a liquid cooling system for even better overclocking.
We measured the power consumption of computer systems with different graphics cards using a multifunctional panel Zalman ZM-MFC3 which can report how much power a computer (the monitor not included) draws from a wall socket. There were two test modes: 2D (editing documents in Microsoft Word and web surfing) and 3D. We ran the benchmark from Metro 2033: The Last Refuge at 2560x1600 with maximum settings as the 3D load because this game could load both the graphics card and CPU. If we ran FurMark, for example, the system’s overall power consumption was 20-25 watts lower than with Metro 2033: The Last Refuge.
So, here are the results:
As you can see, the benefits of the thinner 28nm tech process are negated by the new card’s high clock rates, fast GPU architecture and 384-bit memory bus. The Radeon HD 7970 system needs as much power as the Radeon HD 6970 one. So, AMD was right in writing the same power draw number into the newer card’s specs. We, on our part, should be pleased as we've got higher performance but the same power draw as with the older product.