AMD Radeon HD 7970 GHz Edition Review:Going For The Performance Crown

 NVIDIA launched their GeForce GTX 680 to rave reviews and a boatload of editor recommendations, reclaiming their crown for the fastest single-GPU video card in the process. And for the first time in many years NVIDIA didn’t just beat AMD on raw performance, but they achieved the complete holy trifecta of video card competition – higher gaming performance, lower power consumption, and a lower price.

Consequently, for AMD this launch marked both the closest and the farthest they’ve ever been from outright beating NVIDIA in modern times. On the one hand NVIDIA beat them by more than usual by achieving the holy trifecta as opposed to focusing just on performance. And yet when it comes to raw performance AMD has never been this close. Where the GTX 580 beat the 6970 by 15% the GTX 680 led by just 10%, and even then it lost to the 7970 on some games. With such a close gap an obvious question arises: maybe, just maybe AMD could meet or beat NVIDIA with a higher clocked 7970 and rival them for the performance crown?
Today AMD is putting that idea to the test with the launch of the Radeon HD 7970 GHz Edition. Although AMD is not calling the 7970 GHz Edition a response to the GTX 680 – instead choosing to focus on it being Tahiti’s 6 month birthday – for all intents and purposes this is AMD’s response to the GTX 680. A higher clocked 7970 with AMD’s take on GPU turbo intended to make a run at the GTX 680 and that performance crown.As we’ll see, after today it will no longer be clear who holds the performance crown.

AMD GPU Specification Comparison
	AMD Radeon HD 7970 GHz Edition	AMD Radeon HD 7970	AMD Radeon HD 7950	AMD Radeon HD 6970
Stream Processors	2048	2048	1792	1536
Texture Units	128	128	112	96
ROPs	32	32	32	32
Core Clock	1000MHz	925MHz	800MHz	880MHz
Boost Clock	1050MHz	N/A	N/A	N/A
Memory Clock	6GHz GDDR5	5.5GHz GDDR5	5GHz GDDR5	5.5GHz GDDR5
Memory Bus Width	384-bit	384-bit	384-bit	256-bit
VRAM	3GB	3GB	3GB	2GB
FP64	1/4	1/4	1/4	1/4
Transistor Count	4.31B	4.31B	4.31B	2.64B
PowerTune Limit	250W+	250W	200W	250W
Manufacturing Process	TSMC 28nm	TSMC 28nm	TSMC 28nm	TSMC 40nm
Architecture	GCN	GCN	GCN	VLIW4
Launch Date	06/22/2012	01/09/2012	01/31/2012	12/15/2010
Launch Price	$499	$549	$449	$350

As far as performance and functionality goes, the Radeon HD 7970 GHz Edition (7970GE) is a rather straightforward upgrade to the existing Radeon HD 7970. In fact the hardware is absolutely identical right down to the GPU – there have been no changes to the PCB, the cooling, or the VRMs, and even the Tahiti GPU is the same revision that has been shipping in the 7970 since the beginning. Everything the 7970GE adds to the 7970 is accomplished through chip binning and new Catalyst and BIOS features specific to the 7970GE. So in many ways this is the 7970 we’ve already become familiar with, but with more pep in its step.

With identical hardware the real difference is in clockspeeds. The 7970 shipped at a rather conservative 925MHz core, which as we’ve seen in our 7970 overclocking adventures ends up being a good 175MHz less than what our worst 7970 can hit while overclocked without overvolting. At the time AMD left a lot on the table in order to maximize yields and to give their partners headroom to launch a range of factory overclocked cards, and now AMD has come to take that headroom back for themselves.
The 7970GE will ship at 1GHz, 75MHz faster than the 7970. Furthermore the 7970GE introduces AMD’s PowerTune Technology with Boost, which is AMD’s name for GPU turbo, and similar to the GPU turbo feature that is already on AMD’s APUs. The 7970GE can boost a further 50MHz up to 1050MHz, which means the 7970GE’s core clock increase is anywhere between 8% and 13.5% depending on how high it can go under a specific workload. We’ve seen that AMD’s performance scales very well with clockspeeds – which is to say it’s typically not memory bandwidth bottlenecked – so this bodes well for its performance. All the same AMD has also boosted their memory clocks from 5.5GHz to 6GHz, which will give the card 9% more memory bandwidth with it needs it. AMD hasn’t provided any specific guidance for performance, but overall you can expect around 10% better performance over the 7970 in GPU-bound situations, which is exactly what AMD needs to close the GTX 680 gap.
Beyond the higher clockspeeds and introduction of PowerTune Technology with Boost, that sums up the changes for the 7970GE. There are no board changes and it’s the same Tahiti GPU, meaning 2048 stream processors paired with 128 texture units and 32 ROPs, all on a 4.31B transistor GPU with a die size of 365mm2. With the increase in clockspeed from 7970 this pushes AMD’s theoretical double precision  compute performance over 1 TFLOPs to 1.08 TFLOPs, which AMD is in no way shy about mentioning since they’re the first GPU vendor to get there. On the memory side of things, AMD is using the same 3GB of GDDR5 we’ve previously seen, just clocked higher.

Idential Twins: Radeon HD 7970 GHz Edition & Radeon HD 7970

On that note, because AMD hasn’t made any hardware changes for the 7970GE the 7970GE’s TDP/PowerTune limit is equally unchanged. The 7970GE will have a PowerTune limit of 250W, identical to that of the 7970. With 6 months between the launch of the 7970 and the 7970GE, that’s 6 months of 28nm process improvements over at TSMC, which AMD will be using as the basis of their binning for the 7970GE. With that said there’s no such thing as a free lunch, and in practice the 7970GE’s power consumption has still increased relative to the 7970, as we’ll see in our benchmarks.
On a final point, at this point we would be remiss to not point out that once again AMD has once again added confusion to their product naming system in the name of simplicity. We have always pushed for clear naming schemes where parts with different specifications have different names and for good reason. AMD’s decision to name their new card the 7970 GHz Edition is unfortunate; while it’s true it has the same Tahiti GPU its performance and feature set (PowerTune Boost) are entirely different from the 7970. What’s the point of a 4 digit number if AMD is only ever going to use a fraction of them? In a rational universe this card would be the 7975 and that would be the end of that.
Our primary concern here is that a potential customer is going to read this review and then go out and buy a vanilla 7970 thinking they got the GHz Edition, which is the kind of misleading situation we want product names to avoid. At this point if AMD is going to continue producing multiple products under the name model number – and I can’t believe I’m saying this – they need to bring back proper suffixes. They were less sufferable than “GHz Edition”, which is just long enough to be ignored. At the end of the day clockspeed is not a proper product name.

Anyhow, with clocks and hardware settled, let’s talk about competitive positioning, pricing, and availability. As we alluded to in the introduction, the 7970GE is a clear swipe at the GeForce GTX 680. NVIDIA had a smaller than usual 10% lead with the GTX 680, and as a result AMD is making a run at it with a higher clocked Tahiti part. Realistically speaking, on average AMD can’t beat the GTX 680 with the 7970GE, but with good performance scaling they can tie.
Seeing as how it’s a GTX 680 competitor then, it should come as no surprise that AMD has put the MSRP on the 7970GE at $499, the exact same price as the GTX 680. It’s a slugfest for sure. At the same time it’s no secret that Tahiti cards are relatively expensive to manufacture – thanks to the larger-than-GK104 GPU and 3GB of GDDR5 – so AMD is keen on not just challenging NVIDIA for the crown but also bringing their margins back up to where they were prior to the GTX 680’s launch.
While the price of the 7970 and 7950 aren’t officially changing in the wake of the 7970GE’s launch, the launch of the GTX 600 series has already pushed pricing down to levels below even AMD’s April MSRPs. Reference clocked 7970s are down to around $430 after rebate, and the 7950 (having been pushed out of the picture by the GTX 670) is down to about $360 after rebate. Barring a move from NVIDIA, we expect AMD’s stack to settle here for the time being.
Finally, while general card availability should be good – we’ve already seen that most 7970s can overclock to 7970GE speeds – AMD has pushed the launch out in front of when cards will actually ship. The 7970GE will not appear in stores until next week and widespread availability isn’t expected until July.by ryan smith