With its higher clock speeds, superior stream processor count and more efficient architecture, we were fully expecting the Radeon HD 7970 3GB to offer a substantial increase in performance over the Radeon HD 6970 2GB and it didn't disappoint.
In Arma II
at 1,920 x 1,080 with 4x AA the HD 7970 3GB produced a mighty minimum frame rate of 66fps, matching the dual-GPU HD 6990 4GB due to CPU limitation (yes, from a 3.3GHz Core i5-2500K). This was 18fps faster than its predecessor and 16fps faster than the GeForce GTX 580 1.5GB - a 30 per cent improvement over the Nvidia competition. At 2,560 x 1,600 with 4x AA the minimum frame rate dropped to 41fps, but this was still an incredible 50 per cent faster than the GTX 580 1.5GB.
The performance gap wasn't as wide in Battlefield 3
, but the HD 7970 3GB still impressed with a minimum frame rate of 52fps at 1,920 x 1,080 with 4x AA - 5fps more than the GTX 580 1.5GB and an incredible 16fps (or 44 per cent) faster than the HD 6970 2GB. At 2,560 x 1,600 with 4x AA, the HD 7970 3GB was again extremely capable, with a minimum frame rate of 33fps; 5fps (or 17 per cent) faster than the GTX 580 1.5GB in the same test. While the HD 7970 3GB is certainly significantly faster than its predecessor, its advantage over the GTX 580 1.5GB is smaller in BF3 than in any of our other tests. Clearly the new architecture hasn't been able to solve AMD's poor AA performance with Frostbite 2.
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In Dirt 3
, however, there were no such issues, with the HD 7970 3GB hitting a minimum of 90fps at 1,920 x 1,080 with 4x AA, and a minimum of 64fps at 2,560 x 1,600 with 4x AA. The latter is 20 per cent faster than the GTX 580 1.5GB in the same test, and almost 40 per cent faster than the HD 6970 2GB.
Finally, in Skyrim
, the HD 7970 3GB shared the lower frame rate limit of the other AMD cards at 1,920 x 1,080 with 4x AA of around 50fps, while the Nvidia cards were capable of minimum frame rates of 56-57fps. The result was more telling at 2,560 x 1,600 with 4x AA, with a minimum of 52fps for the HD 7970 3GB, compared with to the GTX 580 1.5GB's 48fps.
Idle power consumption
was impressively low too, being even more frugal than the diminutive HD 6850 1GB. Our test involves leaving the PC to sit idle on the Windows desktop – had we put the screen to sleep, the power draw of the HD 7970 3GB would have been even lower. There's no disguising the card's ravenous power consumption under load though, with the system power rising to 293W when running the Unigine Heaven benchmark. This was substantially more than the HD 6970 2GB in the same test, and even surpassed the GTX 580 1.5GB by 9W.
However, while its peak power consumption might be high, we were greatly impressed by the noise levels of the HD 7970 3GB's stock cooler. Almost inaudible when idle, the fan spun up to a gently audible level under load to keep the GPU temperature below 80°C. The combination of a vapour chamber cooler and clear airflow both into and out of the card worked wonders; in comparison to the faster, but hair-dryer noisy HD 6990 4GB, it's a veritable church mouse.
As the first 28nm GPU, the HD 7970 3GB was always going to be exciting; with such a significant step down in transistor size and subsequent increase in stream processors and clock speeds, the GPU was always going to have enormous performance potential. In Arma II at 2,560 x 1,600 with 4x AA it was an incredible 50 per cent faster than the GeForce GTX 580 1.5GB. This is a one-off result rather than a trend, but for the most part the HD 7970 3GB was still around 20 per cent faster than Nvidia's current single-GPU top dog, if only at ultra-high resolutions such as 2,560 x 1,600 with 4x AA.
However, in comparison to its predecessor, the HD 6970 2GB, it's considerably quicker – in BF3 we saw an increase in speed of 40-50 per cent. Previously we’ve been happy with a 20 per cent jump in performance from one generation of GPUs to the next.
Of course, the dual-GPU HD 6990 4GB and GTX 590 3GB cards are still the fastest. We never expected the HD 7970 3GB to surpass them, but it has certainly closed the gap, especially when overclocked. From our own experiences we fully expect board partners to release cards with GPU frequencies of 1GHz and up, with the pre-requisite price premium of course.
A whole range of 28nms are coming in 2012
Which brings us nicely onto perhaps our biggest concern for the HD 7970 3GB: value. For starters we're not even sure what price it'll launch at when it goes on sale on 9 January 2012. The best estimate is around £440 inc VAT, roughly £60 more than Nvidia’s GeForce GTX 580 1.5GB. That’s fairly reasonable considering the performance advantage on offer.
However, it's questionable whether you seriously need that much graphics performance. With the PC games industry tied down by games that need to be developed for ageing consoles, you won't benefit from this sort of graphics power unless you use very high resolutions. A quick glance at the performance in games such as Skyrim or Dirt 3 at 1,920 x 1,080 is enough to tell you that, for most titles, a cheaper card delivers equally playable results.
Regardless, you'd arguably be foolish (or perhaps an AMD fanboy) to jump the 28nm gun so quickly. Nvidia will respond with its own 28nm Kepler parts around March/April (to coincide with Ivy Bridge, we believe) and we expect new GPUs from AMD between January and March too.
For now, AMD has certainly thrown down the gauntlet. The HD 7970 3GB is a huge improvement over the HD 6970 2GB and GTX 580 1.5GB, and it matches this performance with quiet operation and genuinely useful innovations such as the new ZeroCore technology. Considering its high price and the uncertain nature of the GPU market, though, this is a card for performance junkies with plenty of cash.