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AMD Radeon HD 7970 GHz Edition Video Card Review
Product: AMD Radeon HD 7970 GHz Edition
Author: James Prior
Editor: Charles Oliver
Date: June 21st, 2012
On the half-birthday (June 22) of the AMD Radeon HD 7970's Tahiti GPU, AMD is releasing a new version - the AMD Radeon HD 7970. Oh, and it has a new suffix too, with 6mo. being a long time in the GPU world - it now has letters after its name: GHz Edition. But if you think the new AMD Radeon 7970 GHz Edition is just a clock speed bump, you'd be partially right and partially wrong; while the reference clocks are raised from 925e/1375m to 1000e/1500, there's another trick inside - 50MHz Boost. This new model is a $20 premium over the current 7970 at $499USD SEP and both will stay in market concurrently.
AMD's Tahiti XT was the first 28nm GPU and launched with the AMD Radeon HD 7970 in December 2011, with a slow ramp of availability - high demand and process capacity causing some consternation for eager buyers. Nearly a month later, the Tahiti Pro version launched with the AMD Radeon HD 7950. Two new variants are now coming, Tahiti LE for specific FirePro W-series models and Tahiti XT2, which will appear in at least three new products – the AMD Radeon HD 7970 GHz Edition, the AMD FirePro W6000, and the AMD Radeon dual-GPU product codenamed New Zealand.
The Tahiti XT2 specification is a result of the learning process AMD went through for the first GPU - a 'pipecleaner' process if you will. The results of this knowledge were evident quickly for AMD, with both the 7800 and 7700 series chips (Pitcairn and Cape Verde, respectively) launching with GHz Edition specifications. AMD weren't content with leaving Tahiti where it was, especially since NVIDIA came to 28nm with the big-gpu-from-little-die Kepler 104 that ended up winning the performance crown.
Binning, the process by which the 7970 and 7950 chips are sorted, is responsible for the new Tahiti XT2 chips; there were no process improvements or stepping changes. That's not to say there isn't any engineering effort in Tahiti XT2, there is but in a different area - power management. AMD engineering spent a lot of time looking at how to make PowerTune better and they've improved not only the monitoring latency but the clock adjustment - now we get dynamic engine clock boost based on hardware workload performance analysis.
AMD's PowerTune allows 256 discrete clock states with four voltage levels. Boost leverages this to run at a specified 3D engine clock, 1000MHz, at a lower voltage than the original Tahiti XT uses to run 925MHz. The fourth state is used when PowerTune looks through the GPU and decides that turning up the wick - 1050MHz engine clock rate - would be beneficial to the workload without violating the thermal envelope the card is running inside. This is known as Boost, or high performance clock rate. All cards get the same boost clock rate from the factory, but AIBs will be able to adjust the voltage and high performance clock for their customized models.
AMD claims the new Radeon HD 7970 GHz Edition is the world's fastest graphics card, using their performance testing vs. the GeForce GTX 680. Their testing focuses on high resolution and high quality settings, the area where AMD's current Radeon HD 7970 is strongest against the little Kepler that could. AMD has always maintained that for 'mainstream' resolutions like 1920x1080 their second tier GPU, the Radeon 7800 series, might be a better option for the performance gamer. Enthusiast gamers, they argue, like big resolution, big quality, and that's where the 7900 series stretches its legs best.