AMD Radeon HD 7970 GHz Edition £420
22nd Jun 2012 | 04:01
Are you finished, Nvidia? Well, then allow AMD to retort…
Introduction and Architecture
AMD's Radeon HD 7970 reached its six-month birthday on June 22nd 2012, and to celebrate AMD has released a card that's just, well, better: the AMD Radeon HD 7970 GHz Edition.
Since it released the original Radeon HD 7970, in December last, the top single-GPU graphics card crown has slipped from its once mighty, and once mightily expensive, head. Nvidia waited, holding its breath until March, when it released its top consumer spin of the new Kepler architecture, the Nvidia GeForce GTX 680.
That came in slightly undercutting the Radeon card and just about pipping it to the benchmark crown in most of our tests. Not just that but the Nvidia GTX 680 managed it with a far smaller and more efficient GPU.
To most of us that came as something of a surprise.
AMD traditionally had the reputation of releasing the more efficient GPUs of a generation with Nvidia usually the ones employing a brute force approach with a big, hot and powerful chip at the heart of its latest architecture.
That switch wasn't the only one of this latest generation either. AMD's Graphics Core Next (GCN) architecture - which makes up the Southern Island series of HD 7000 graphics cards - was conceived with a view to creating a much more compute focused card. Previous to this architecture AMD had focused on creating pure gaming cards with only a faint nod towards GPGPU processing.
Nvidia, on the other hand, chose performance per Watt for its consumer cards and sacrificed the GPGPU computing power that had been central to the Fermi architecture. This cut-down GPU though was still a great gaming chip, as the Nvidia GeForce GTX 680 showed, leaving the Tesla team, with the GK110 K20, to the pro-graphics compute shizzle.
Still, it managed to best AMD's top card in most gaming benchmarks leaving it with the runners up prize.
GPU - Tahiti XT
Process - 28nm
Clockspeed - 1,050MHz
Memory capacity - 3GB GDDR5
Memory bus - 384-bit
The AMD Radeon HD 7970 GHz Edition is the Texan company's counter-offer to gamers in light of the slight lead Nvidia managed with the GTX 680. And to be fair, it's come up with quite an interesting proposal.
The salient point here though is that AMD has reclaimed the outright single-GPU performance crown of this generation. Obviously that's discounting the twin-GPU toting Nvidia GTX 690, which has almost cheated its way to the top of the graphics card pile.
Though AMD had planned an assault on even that position, promising us the card once code-named as New Zealand. You know, the place that has two Southern Islands making up the country.
Still, for whatever reason that card is off the table now with AMD focusing its efforts on bolstering the Tahiti GPU-sporting HD 7970 and making it the top single-GPU card around.
So, how has it managed this feat?
Well, the simple answer is overclocking. We told you it was simple.
But this isn't quite the traditional card speed bump, or manufacturer-supported factory overclocked card you might normally expect. Nothing has actually changed regarding the GPU itself.
AMD is still taking them from the same wafers, with the same designs, but it has taken the six months of learning that went into the subsequent Pitcairn and Cape Verde GPUs and applied it to the flagship chip. Basically the GPU manufacturing process has matured and so has the technology and, most importantly, the software.
This has enabled AMD to get more top-end Tahiti cores out of the wafers and so is offering the AMD Radeon HD 7970 GHz Edition with a clockspeed of, you guessed it, 1GHz.
Though that's not strictly true.
In reality the clockspeed you're realistically going to get when gaming is actually 1.05GHz.
That extra 50MHz coming from something AMD is calling PowerTune with Boost. The idea being similar in concept to Nvidia's GPU Boost, with some new hardware on the PCB monitoring the voltage and offering extra power, up to that 1.05GHz mark, when the thermal headroom allows.
In our testing that was all of the time, even with the standard reference cooler design. Our reference AMD Radeon HD 7970 GHz Edition sat at a stable 1.05GHz for the entire time the GPU was pushed to 100% load.
The only other real addition of note to the card is the 3GB of GDDR5 graphics memory has been given a bit of a speed boost too. The stock card has a 1,375MHz speed for its memory while the AMD Radeon HD 7970 GHz Edition comes with the VRAM running at a healthy 1,500MHz.
That's not all though as the type of memory used has been changed too. This time it is using the faster 6Gbps VRAM over the 5.5Gbps chips it had been rocking, the same speedy memory the Nvidia GTX 680 is sporting then.
Thanks to AMD's faster 384-bit memory bus though the Radeon HD 7970 GHz Edition has a massive 288GB/s memory bandwidth compared with the 192GB/s of the top single-GPU Nvidia card. That means at the higher end of the resolution spectrum the AMD card now seriously has the edge.
We tested all three cards here at the 30-inch panel resolution of 2560x1600 with all settings pushed right up to really stress the GPUs.
With a smaller 1080p screen you're not really going to be testing a high-end graphics card like any of these, and you're going to be far better off spending your money on a second tier GPU. These top-end cards are for the seriously high-res gamer.
The really interesting thing here, aside from the AMD card taking top honours almost across the board, is the compute performance of the AMD versus the Nvidia cards.
In the DirectCompute titles, DiRT Showdown and Sniper Elite V2, the AMD GPU has a strong lead over the Nvidia competition. If more games go down the compute route to improve post-processing and other effects then Nvidia's current top-GPU might be in trouble.
That said we all know the monstrous GK110 GPU is just begging to be dropped into a serious gaming rig. And that sounds like it would eat through computational tasks with abandon.
At the moment though, we tip our hat to AMD for making the Radeon HD 7970 GHz Edition a blazing-fast graphics card.
DirectX 11 synthetic tessellation performance
DirectX 11 gaming tessellation performance
DirectX 11 gaming performance
DirectX 10 gaming performance
OpenCL raytracing performance
OpenCL processing performance
At £420 ($500) the AMD Radeon HD 7970 GHz Edition is being aimed squarely at the Nvidia GTX 680, and in practically all of our benchmarks it has the edge over the green team's card. Possibly the most damning of those benchmarks though is in the two latest games in our suite of tests; DiRT Showdown and Sniper Elite V2.
Both of these titles use the DirectCompute component of DirectX to create some of their effects, like Global Illumination in the case of DiRT Showdown and compute-assisted antialiasing in Sniper Elite V2. Both of these technologies show how wise it might prove for AMD to gamble on its compute-focused architecture in terms of new game engines.
And possibly how ill-advised Nvidia was to drop that focus in the consumer variants of its Kepler architecture.
But these are only two titles, though AMD will be hoping that other developers start to use the processing capabilities of its GPUs for game-centric effects other than traditional graphics. The performance gap between AMD and Nvidia in these titles may be closed in future driver releases by the green side of the graphics divide, but our benchmarks were taken using the very latest Nvidia drivers available to us.
As it stands though, in these compute-focused game engines the Kepler architecture really suffers in comparison with the Tahiti XT GPU in the AMD Radeon HD 7970 GHz Edition. In DiRT Showdown the GTX 680 is almost half the speed of the new Radeon card.
When you look at tessellation-heavy titles like Metro 2033 and synthetic GPGPU tests like SiSoft Sandra and Lux Mark that failing is just as evident.
So it's tangibly faster than the GTX 680, but how does it fare against its older brother, the stock Radeon HD 7970?
Well, this is where things get rather stickier for the new AMD HD 7970 GHz Edition.
The price of the original HD 7970 has dropped by around £100 since launch, and isn't too far off the performance of either its GHz Edition brethren or the GTX 680 in reference trim. The original Tahiti XT though still has some overclocking chops and all it takes is a little check box and a couple of sliders in the AMD Catalyst Control Centre to get the old GPU up to the same speeds as this new GPU league leader.
With the same clockspeeds the reference card is almost the same speed in benchmarking terms as the new GHz Edition. The extra memory bandwidth of the newer card allows for slightly higher frame rates at the highest resolutions with serious AA enabled, but the differences are barely noticeable in game.
And that also means it's faster than the stock GTX 680. Obviously the Nvidia card though can still be overclocked further so it can maintain some pride in the benchmark stakes.The other snag is the likes of the Zotac GTX 670 AMP! Edition with very similar performance chops and the same significant difference in price compared with the new GHz Edition.
The weird thing then is the fact that AMD is still keeping the standard HD 7970 alive in the graphics card lineup, with the GHz Edition simply taking its place higher in the price ladder.
So while the AMD Radeon HD 7970 GHz Edition can lay claim to the fastest single-GPU card crown we still feel that AMD is somehow missing a bit of a trick. By releasing it at the same price as the GTX 680 it's challenging buyers to make the choice. By pricing it significantly below the Nvidia price tag it could have simply removed that element of choice. You would be mad to opt for a GTX 680 if the price were any different.
As it is at the top now you have to make the choice as to whether you pick up the Nvidia GTX 680 with a weakness for compute-focused gaming, but a wealth of developers happily ensconced in its 'The Way It's Meant To Be Played' program, and also having fun with its Apex suite of PhysX goodies.
The other option is this AMD Radeon HD 7970 GHz Edition with its straight performance lead and a penchant for serious computing power.
We'd rather AMD had made a stand and put this GHz Edition out seriously undercutting the Nvidia competition, but as it is this new card stands out at the top of the performance charts and is blazing new ground in the compute-heavy gaming arena.
We love the fact AMD has managed to tweak its drivers and speed dials to the extent it now has the top single-GPU card out there.
The Tahiti XT GPU also shows it's impressive compute performance chops too in this latest round - ably highlighted by the DiRT Showdown and Sniper Elite V2 benchmarks. If this is the way 3D game engines are going Nvidia will have to rethink its architectural focus.
It may well be the fastest single-GPU card on the market, but it is still essentially just a factory overclocked card that AMD is selling as completely new addition to its graphics card lineup.
And that doesn't warrant the hefty price premium that AMD is slapping on this sped up version of its existing cards.
You could save yourself some money and get similar performance out of an original HD 7970 and overclock it a little. Or you could overclock it more...
A great refresh of the HD 7970, but doesn't warrant the massive price premium over the original.