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Radeon HD 6970 And 6950 Review: Is Cayman A Gator Or A Crock?

Radeon HD 6970 And 6950 Review: Is Cayman A Gator Or A Crock?
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Last month, Nvidia launched its GeForce GTX 580, but we told you to hold off on buying it. A week ago, Nvidia launched GeForce GTX 570 and we again said "wait." AMD's Cayman was our impetus. Were Radeon HD 6970 and 6950 worth the wait? Read on for more!

In the world of high-end hardware, waiting for the next great thing means reading about a lot of technology and never actually buying a new piece of gear. That’s no way to enjoy your favorite games though, is it?

Sometimes the wait is worth it, though. Last week was a perfect example. Nvidia launched its GeForce GTX 570, but we already knew AMD’s Radeon HD 6970 and 6950 boards had shipped out, FedEx Next Day Air. How could we not recommend waiting to see how these boards would compare? The very same morning, AMD launched a refresh on its Phenom II and Athlon II processors, incrementing clock rate. But we have Intel’s Sandy Bridge-based CPUs up and running in the lab. Again—why wouldn’t you wait a couple of weeks to see how they stack up?

Anticipating Greatness

I was particularly interested in the performance of the Radeon HD 6970 and 6950, the two cards AMD had shipped so urgently. Whereas the Barts GPUs used to build Radeon HD 6870 and 6850 centered on the same VLIW5 architecture that earned Radeon HD 5870 a place in infamy, the Cayman GPU consolidates functionality into a VLIW4 design, incorporating fewer ALUs per thread processor, but improving performance per square millimeter of die space. How would that translate to the experience you get when you plug a 6900-series card into your system? Well, since Cayman is larger than Cypress, we have to assume it’s also going to be faster.

A market populated by GF100-based boards like GeForce GTX 480 and GeForce GTX 470 would have made this launch so much easier for AMD. But Nvidia has this habit of kicking into gear when it really needs to. The resulting GeForce GTX 580 and 570 demonstrate that, even if Fermi remains a power-hungry architecture, it is possible to contend with more heat using a better sink and finely-tuned fan control. Suddenly, AMD had a much more daunting competitive landscape in front of it.

We’re not sure if that was the real reason AMD’s Radeon HD 6900-series cards were delayed for nearly a month. However, the boards are here now (two of each, actually), and AMD claims that channel availability will be plentiful right out of the gate.

Look familiar? That's the 5870's CypressLook familiar? That's the 5870's Cypress

New GPU, Familiar Face

AMD’s GPU team isn’t known for its bold, brash architectural moves—that honor belongs to Nvidia—so it’s hardly a surprise that much of Cayman looks familiar. In fact, there was no fancy press day hosted on an aircraft carrier to herald the improvements, nor were there conversations with chip architects. After the fanfare ahead of Radeon HD 6800, today's 6900-series launch was preceded by surprisingly little commotion. It was almost…refreshing. That gave us plenty of time to dig into the details for ourselves. Fortunately, we know enough about AMD's Cayman GPU to discuss what changes.

Very similar: The 6900-series' CaymanVery similar: The 6900-series' Cayman

Fully loaded, the chip features up to 24 SIMD engines (up from Cypress’ 20). Each SIMD still includes 16 thread processors. Except now, each thread processor consists of four ALUs rather than five. So, while Cypress sported as many as 1600 ALUs, Cayman incorporates up to 1536 (that’s 24 * 16 * 4). Each SIMD engine is still tied to four texture units, totaling 96 on a complete Cayman chip (versus 80 on Cypress).


AMD Radeon HD 6970
AMD Radeon HD 6950
AMD Radeon HD 5870
Nvidia GeForce GTX 580
Manufacturing Process
40 nm TSMC
40 nm TSMC
40 nm TSMC
40 nm TSMC
Die Size
389 mm²389 mm²334 mm²520 mm²
Transistors
2.64 billion
2.64 billion
2.15 billion
3 billion
Engine Clock
880 MHz
800 MHz
850 MHz
772 MHz
Stream Processors / CUDA Cores
1536
1408
1600
512
Compute Performance
2.7 TFLOPS
2.25 TFLOPS
2.7 TFLOPS
1.58 TFLOPS
Texture Units
96
88
80
64
Texture Fillrate
84.5 Gtex/s
70.4 Gtex/s
68 Gtex/s
49.4 Gtex/s
ROPs
32
32
32
48
Pixel Fillrate
28.2 Gpix/s
25.6 Gpix/s
27.2 Gpix/s
37.1 Gpix/s
Frame Buffer
2 GB GDDR5
2 GB GDDR5
1 GB GDDR5
1.5 GB GDDR5
Memory Clock
1375 MHz
1250 MHz
1200 MHz
1002 MHz
Memory Bandwidth
176 GB/s (256-bit)
160 GB/s (256-bit)
153.6 GB/s (256-bit)
192 GB/s (384-bit)
Maximum Board Power
250 W
200 W
188 W
244 W


As with the Cypress and Barts GPUs, Cayman is a product of TSMC’s now-mature 40 nm manufacturing process. It probably wouldn’t have been, but TSMC canceled its 32 nm node back in 2009, leaving both AMD and Nvidia to rethink their strategies. The aforementioned specs allowed AMD to keep its die size manageable, while still improving performance, though. Cayman is a 389 mm² piece of silicon composed of 2.64 billion transistors, while Cypress was 334 mm² part made up of 2.15 billion transistors. What AMD didn’t want to do was follow in Nvidia’s footsteps, creating a 500+ mm² behemoth that it’d need to power and then cool. From all angles, Cayman looks to be a compromise based on the hand TSMC dealt.

It seems that the company was able to turn those lemons into something more palatable, though, by getting inventive with a feature called PowerTune, which balances TDP to facilitate higher shipping clock speeds. The two resulting board models, Radeon HD 6970 and 6950 handily outperform AMD’s last at-bat on the 40 nm process. The real question is, can they stack up to the more recent and renewed competition from Nvidia?

Ten points, by the way, if you can figure out the reference in this story’s title.

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Top Comments
  • 30 Hide
    terror112 , December 15, 2010 3:13 AM
    WOW not impressed.
  • 15 Hide
    iam2thecrowe , December 15, 2010 4:22 AM
    Dissappointed. well i guess anyone that bought a 5xxx series card that couldnt wait can now be content that they made an ok choice. The only thing i got from this review is that i want 2 x gtx460's or 2 x 6850's, not the new amd cards.
  • 14 Hide
    bluekoala , December 15, 2010 4:56 AM
    I also urge people to put more emphasis on MINIMUM FPS as that is when you require high FPS the most.
Other Comments
  • 30 Hide
    terror112 , December 15, 2010 3:13 AM
    WOW not impressed.
  • 11 Hide
    Annisman , December 15, 2010 3:15 AM
    Thanks for the review Angelini, these new naming schemes are hurting my head, sometimes the only way to tell (at a quick glance) which AMD card matches up to what Nvidia card, is by comparing the prices, which I think is bad for the average consumer.
  • 13 Hide
    rohitbaran , December 15, 2010 3:25 AM
    These cards are to GTX 500 series what 4000 series was to GTX 200. Not the fastest at their time but offer killer performance and feature set for the price. I too expected 6900 to be close to GTX 580, but it didn't turn out that way. Still, it is the card I have waited for to upgrade. Right in my budget.
  • 3 Hide
    tacoslave , December 15, 2010 3:25 AM
    imagine when this hits 32nm?
  • 7 Hide
    notty22 , December 15, 2010 3:27 AM
    AMD's top card is about a draw with the gtx 570.
    Pricing is in line.
    Gives AMD only hold outs buying options, Nvidia already offered
    Merry Christmas
  • 11 Hide
    microterf , December 15, 2010 3:27 AM
    Why drop the 580 when it comes to the multi-gpu scaling??
  • 4 Hide
    IzzyCraft , December 15, 2010 3:28 AM
    Sorry all i read was this
    "This helps catch AMD up to Nvidia. However, Intel has something waiting in the wings that’ll take both graphics companies by surprise. In a couple of weeks, we'll be able to tell you more." and now i'm fixated to weather or not intel's gpu's can actually commit to proper playback.
  • -3 Hide
    andrewcutter , December 15, 2010 3:28 AM
    but from what i read at hardocp, though it is priced alongside the 570, 6970 was benched against the 580 and they were trading blows... So toms has it at par with 570 but hard has it on par with 580.. now im confused because if it can give 580 perfomance or almost 580 performance at 570 price and power then this one is a winner. Sim a 6950 was trading blows with 570 there. So i am very confused
  • -1 Hide
    sgt bombulous , December 15, 2010 3:30 AM
    This is hilarious... How long ago was it that there were ATI fanboys blabbering "The 6970 is gonna be 80% faster than the GTX 580!!!". And then reality hit...
  • 2 Hide
    manitoublack , December 15, 2010 3:35 AM
    I'd have to say wait until the christmas new years dust settles
  • 8 Hide
    andrewcutter , December 15, 2010 3:36 AM
    sry i take back what i said earlier. most reviews agree with what toms says. So my apologies..:) 
  • 6 Hide
    tpi2007 , December 15, 2010 3:36 AM
    Not bad, but not very impressive either. It's hard to be impressed at 40nm by now.

    But it is quite ironic that AMD has had a tesselator in their cards way before anybody supported the feature (let alone Nvidia), and now Nvidia does better tessellation than AMD.. they should really address that problem.. well, now the only way is to redesign the chip... at 28nm.

    28nm it is then, the next big excitment.

    What I would really like, now that the HD6xxx lineup is here (dual GPU still missing, but that is a niche product), is that AMD now focuses on fixing bugs in their drivers.
  • 4 Hide
    namelessonez , December 15, 2010 3:39 AM
    It's always the same story! nVidia pulls out a new product and then the wait begins for AMD to release its products! Ultimately, the difference isn't worth the wait. We know that AMD's winning factor is its price, but nVidia's is the quality....imho!

    As rightly stated, 'reality hits'.
  • 0 Hide
    yyk71200 , December 15, 2010 3:50 AM
    AndrewCutterbut from what i read at hardocp, though it is priced alongside the 570, 6970 was benched against the 580 and they were trading blows... So toms has it at par with 570 but hard has it on par with 580.. now im confused because if it can give 580 perfomance or almost 580 performance at 570 price and power then this one is a winner. Sim a 6950 was trading blows with 570 there. So i am very confused

    Actually, in Hardocp review overall 580 has some edge over 6970 as well. Only in F1 6970 is ahead. 6970 is great value though.
  • 8 Hide
    joytech22 , December 15, 2010 3:52 AM
    IzzyCraftSorry all i read was this"This helps catch AMD up to Nvidia. However, Intel has something waiting in the wings that’ll take both graphics companies by surprise. In a couple of weeks, we'll be able to tell you more." and now i'm fixated to weather or not intel's gpu's can actually commit to proper playback.


    If intel entered the graphics market and provided a half-decent dedicated GPU, that would definitely make ANY GPU company shake in their boots.

    But in all honesty i hope Intel does enter the market for graphics, making AMD and Nvidia push harder and faster for better products.
  • 1 Hide
    Stardude82 , December 15, 2010 3:53 AM
    So the answer to the question posed in the title is that it is neither really a gator nor a crock. It works on so many levels! Well, maybe just one since caimans are more closely related to alligators than crocodiles.
  • 10 Hide
    Tamz_msc , December 15, 2010 3:54 AM
    I wonder if Nvidia will reduce the prices on the GTX 580 and 570.
  • 6 Hide
    Lamiel , December 15, 2010 4:02 AM
    About the only good news I can see in this for AMD is how much they've increased their multi-GPU scaling, making the 6850's in Crossfire a great bargain. That's great, sure, but the new 6900 cards leave me completely underwhelmed. It doesn't make a whole lot of sense to follow up the 6800's in this way. I'm an Nvidia user, but I was still looking forward with curiosity to seeing how much stronger the 6970 would be than the GTX 580. Looks like the hype-machine broke down this time... My guess is that a lot of the AMD/ATI fanatics will be scrambling to salvage some dignity after all their talking up of Cayman and how it would eat Nvidia's lunch.
  • -3 Hide
    fstrthnu , December 15, 2010 4:16 AM
    This reminds me a lot about the recent release of the updated AMD processors - a temporary holdout while the company plans to release new ones ahead. Except these graphics cards don't even have value going for them. Nvidia was behind just a couple months ago, but now they're ready to crush AMD/Radeon. AMD better have something new coming, and FAST. Holding procedures will only do so much when your competitor is already developing their next-gen GPUs.
  • 15 Hide
    iam2thecrowe , December 15, 2010 4:22 AM
    Dissappointed. well i guess anyone that bought a 5xxx series card that couldnt wait can now be content that they made an ok choice. The only thing i got from this review is that i want 2 x gtx460's or 2 x 6850's, not the new amd cards.
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