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While AMD and NVIDIA are consistently revising their GPU architectures, for the most part the changes they make are just that: revisions. It’s only once in a great while that a GPU architecture is thrown out entirely, which makes the arrival of a new architecture a monumental occasion in the GPU industry. The last time we saw this happen was in 2006/2007, when unified shaders and DirectX 10 lead to AMD and NVIDIA developing brand new architectures for their GPUs. Since then there have been some important revisions such as AMD’s VLIW4 architecture and NVIDIA’s Fermi architecture, but so far nothing has quite compared to 2006/2007, until now.

At AMD’s Fusion Developer Summit 2011 AMD announced Graphics Core Next, their next-generation GPU architecture. GCN would be AMD’s Fermi moment, where AMD got serious about GPU computing and finally built an architecture that would serve as both a graphics workhorse and a computing workhorse. With the ever increasing costs of high-end GPU development it’s not enough to merely develop graphics GPUs, GPU developers must expand into GPU computing in order to capture the market share they need to live well into the future.

At the same time, by canceling their 32nm process TSMC has directed a lot of hype about future GPU development onto the 28nm process, where the next generation of GPUs would be developed. In an industry accustomed to rapid change and even more rapid improvement never before have GPU developers and their buyers had to wait a full 2 years for a new fabrication process to come online.

All of this has lead to a perfect storm of anticipation for what has become the Radeon HD 7970: not only is it the first video card based on a 28nm GPU, but it’s the first member of the Southern Islands and by extension the first video card to implement GCN. As a result the Radeon HD 7970 has a tough job to fill, as a gaming card it not only needs to deliver the next-generation performance gamers expect, but as the first GCN part it needs to prove that AMD’s GCN architecture is going to make them a competitor in the GPU computing space. Can the 7970 do all of these things and live up to the anticipation? Let’s find out…

AMD GPU Specification Comparison
  AMD Radeon HD 7970 AMD Radeon HD 6970 AMD Radeon HD 6870 AMD Radeon HD 5870
Stream Processors 2048 1536 1120 1600
Texture Units 128 96 56 80
ROPs 32 32 32 32
Core Clock 925MHz 880MHz 900MHz 850MHz
Memory Clock 1.375GHz (5.5GHz effective) GDDR5 1.375GHz (5.5GHz effective) GDDR5 1.05GHz (4.2GHz effective) GDDR5 1.2GHz (4.8GHz effective) GDDR5
Memory Bus Width 384-bit 256-bit 256-bit 256-bit
Frame Buffer 3GB 2GB 1GB 1GB
FP64 1/4 1/4 N/A 1/5
Transistor Count 4.31B 2.64B 1.7B 2.15B
Manufacturing Process TSMC 28nm TSMC 40nm TSMC 40nm TSMC 40nm
Price Point $549 $350 $160 -

The Radeon HD 7970 is a card of many firsts. It’s the first video card using a 28nm GPU. It’s the first card supporting Direct3D 11.1. It’s the first member of AMD’s new Southern Islands Family. And it’s the first video card implementing AMD’s Graphics Core Next architecture. All of these attributes combine to make the 7970 quite a different video card from any AMD video card before it.

Cutting right to the chase, the 7970 will serve as AMD’s flagship video card for the Southern Islands family. Based on a complete AMD Tahiti GPU, it has 2048 stream processors organized according to AMD’s new SIMD-based GCN architecture. With so many stream processors coupled with a 384bit GDDR5 memory bus, it’s no surprise that Tahiti is has the highest transistor count of any GPU yet: 4.31B transistors. Fabricated on TSMC’s new 28nm High-K process, this gives it a die size of 365mm2, making it only slightly smaller than AMD’s 40nm Cayman GPU at 389mm2.

Looking at specifications specific to the 7970, AMD will be clocking it at 925MHz, giving it 3.79TFLOPs of theoretical computing performance compared to 2.7TFLOPs under the much different VLIW4 architecture of the 6970. Meanwhile the wider 384bit GDDR5 memory bus for 7970 will be clocked at 1.375GHz (5.5GHz data rate), giving it 264GB/sec of memory bandwidth, a significant jump over the 176GB/sec of the 6970.

These functional units are joined by a number of other elements, including 8 ROP partitions that can process 32 ROPs per clock, 128 texture units divided up among 32 Compute Units (CUs), and a fixed function pipeline that contains a pair of AMD’s 9th generation geometry engines. Of course all of this hardware would normally take quite a bit of power to run, but thankfully power usage is kept in check by the advancements offered by TSMC’s 28nm process. AMD hasn’t provided us with an official typical board power, but we estimate it’s around 220W, with an absolute 250W PowerTune limit. Meanwhile idle power usage is looking particularly good, as thanks to AMD's further work on power savings their typical power consumption under idle is only 15W. And with AMD's new ZeroCore Power technology (more on that in a bit), idle power usage drops to an asbolutely miniscule 3W.

Overall for those of you looking for a quick summary of performance, the 7970 is quite powerful, but it may not be as powerful as you were expecting. Depending on the game being tested it’s anywhere between 5% and 35% faster than NVIDIA’s GeForce GTX 580, averaging 15% to 25% depending on the specific resolution in use. Furthermore thanks to TSMC’s 28nm process power usage is upwards of 50W lower than the GTX 580, but it’s still higher than the 6970 it replaces. As far as performance jumps go from new fabrication processes, this isn’t as big a leap as we’ve seen in the past.

In a significant departure from the launch of the Radeon HD 5870 and 4870, AMD will not be pricing the 7970 nearly as aggressively as those cards with its launch. The MSRP for the 7970 will be $550, a premium price befitting a premium card, but a price based almost exclusively on the competition (e.g. the GTX 580) rather than one that takes advantage of cheaper manufacturing costs to aggressively undercuts the competition. In time AMD needs to bring down the price of the card, but for the time being they will be charging a price premium reflecting the card’s status as the single-GPU king.

For those of you trying to decide whether to get a 7970, you will have some time to decide. This is a soft launch; AMD will not make the 7970 available until January 9th (the day before the Consumer Electronics Show), nearly 3 weeks from now. We don’t have any idea what the launch quantities will be like, but from what we hear TSMC’s 28nm process has finally reached reasonable yields, so AMD should be in a better position than the 5870 launch. The price premium on the card will also help taper demand side some, though even at $550 this won’t rule out the first batch of cards selling out.

Beyond January 9th, AMD as an entire family of Southern Islands video cards still to launch. AMD will reveal more about those in due time, but as with the Evergreen and Northern Islands families AMD has a plan to introduce a number of video cards over the next year. So 7970 is just the beginning.

Winter 2011 GPU Pricing Comparison
AMD Price NVIDIA
  $750 GeForce GTX 590
Radeon HD 6990 $700  
Radeon HD 7970 $549  
  $500 GeForce GTX 580
Radeon HD 6970 $350 GeForce GTX 570
Radeon HD 6950 2GB $250  
  $240 GeForce GTX 560 Ti
Radeon HD 6870 $160  

 

A Quick Refresher: Graphics Core Next
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  • CeriseCogburn - Thursday, March 08, 2012 - link

    That happened at the end of 2006 with the G80 Roald. That means AMD and their ATI Radeon aquisition crew are five years plus late to the party.
    FIVE YEARS LATE.
    It's nice to know that what Nvidia did years ago and recently as well is now supported by more people as amd copycats the true leader.
    Good deal.
    Reply
  • Hauk - Thursday, December 22, 2011 - link

    A stunningly comprehensive analysis of this new architecture. This is what sets Anandtech apart from its competition. Kudos Ryan, this is one of your best.. Reply
  • eastyy - Thursday, December 22, 2011 - link

    its funny though when it comes to new hardware you read these complicated technical jargon and lots of detailed specs about how cards do things different how much more technically complicated and in the end for me all it means is...+15fps and thats about it

    as soon as a card comes out for say 150 and the games i play become slow and jerky on my 460 then i will upgrade
    Reply
  • Mockingbird - Thursday, December 22, 2011 - link

    I'd like to see some benchmarks on FX-8150 based system (990fx) Reply
  • piroroadkill - Friday, December 23, 2011 - link

    Haha, the irony is that AMD is putting out graphics cards that would be bottlenecked HARDCORE by ANY of their CPUs, overclocked as much as you like.

    It's kind of tragic...
    Reply
  • Pantsu - Friday, December 23, 2011 - link

    The performance increase was as expected, at least for me, certainly not for all those who thought this would double performance. Considering AMD had a 389mm^2 chip with Cayman, they weren't going to double the transistor count again. That would've meant the next gen after this would be Nvidia class huge ass chip. So 64% more transistors on a 365mm^2 chip. Looks like transistor density increase took a bit of a hit on 28nm, perhaps because of 384-bit bus? Still I think AMD is doing better than Nvidia when it comes to density.

    As far as the chip size is concerned, the performance is OK, but I really question whether 32 ROPs is enough on this design. Fermi has 48 ROPs and about a billion transistors less. I think AMD is losing AA performance due to such a skimpy ROP count.

    Overall the card is good regardless, but the pricing is indeed steep. I'm sure people will buy it nonetheless, but as a 365mm^2 chip with 3GB GDDR5 I feel like it should be 100$ cheaper than what it is now. I blame lack of competition. It's Nvidia's time to drop the prices. GTX 580 is simply not worth that much compared to what 6950/560Ti are going for these days. And in turn that should drop 7970/50 price.
    Reply
  • nadavvadan - Friday, December 23, 2011 - link

    Am I really tired, or is:
    " 3.79TFLOPs, while its FP64 performance is ¼ that at 947MFLOPs"
    supposed to be:
    " 3.79TFLOPs, while its FP64 performance is ¼ that at 947-G-FLOPs"?

    Enjoyed the review as always.
    Reply
  • Death666Angel - Friday, December 23, 2011 - link

    Now that you have changed the benchmark, would it be possible to publish a .pdf with the relevant settings of each game? I would be very interested to replicate some of the tests with my home system to better compare some results. If it is not too much work that is (and others are interested in this as well). :D Reply
  • marc1000 - Friday, December 23, 2011 - link

    What about juniper? Could it make it's way to the 7000 series as a 7670 card? Of course, upgraded to GCN, but with same specs as current cards. I guess that at 28nm it would be possible to abandon the pci-e power requirement, making it the go-to card for oem's and low power/noise systems.

    I would not buy it because I own one now, but I'm looking forward to 7770 or 7870 and their nvidia equivalent. It looks like next year will be a great time to upgrade for who is in the middle cards market.
    Reply
  • Scali - Saturday, December 24, 2011 - link

    I have never heard Jen-Hsun call the mock-up a working board.
    They DID however have working boards on which they demonstrated the tech-demos.
    Stop trying to make something out of nothing.
    Reply

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