• What
    is this?

    You've landed on the AMD Portal on AnandTech. This section is sponsored by AMD. It features a collection of all of our independent AMD content, as well as Tweets & News from AMD directly. AMD will also be running a couple of huge giveaways here so check back for those.

    PRESENTED BY

Cayman: The Last 32nm Castaway

With the launch of the Barts GPU and the 6800 series, we touched on the fact that AMD was counting on the 32nm process to give them a half-node shrink to take them in to 2011. When TSMC fell behind schedule on the 40nm process, and then the 32nm process before canceling it outright, AMD had to start moving on plans for a new generation of 40nm products instead.

The 32nm predecessor of Barts was among the earlier projects to be sent to 40nm. This was due to the fact that before 32nm was even canceled, TSMC’s pricing was going to make 32nm more expensive per transistor than 40nm, a problem for a mid-range part where AMD has specific margins they’d like to hit. Had Barts been made on the 32nm process as projected, it would have been more expensive to make than on the 40nm process, even though the 32nm version would be smaller. Thus 32nm was uneconomical for gaming GPUs, and Barts was moved to the 40nm process.

Cayman on the other hand was going to be a high-end part. Certainly being uneconomical is undesirable, but high-end parts carry high margins, especially if they can be sold in the professional market as compute products (just ask NVIDIA). As such, while Barts went to 40nm, Cayman’s predecessor stayed on the 32nm process until the very end. The Cayman team did begin planning to move back to 40nm before TSMC officially canceled the 32nm process, but if AMD had a choice at the time they would have rather had Cayman on the 32nm process.

As a result the Cayman we’re seeing today is not what AMD originally envisioned as a 32nm part. AMD won’t tell us everything that they had to give up to create the 40nm Cayman (there has to be a few surprises for 28nm) but we do know a few things. First and foremost was size; AMD’s small die strategy is not dead, but getting the boot from the 32nm process does take the wind out of it. At 389mm2 Cayman is the largest AMD GPU since the disastrous R600, and well off the sub-300mm2 size that the small die strategy dictates. In terms of efficient usage of space though AMD is doing quite well; Cayman has 2.64 billion transistors, 500mil more than Cypress. AMD was able to pack 29% more transistors in only 16% more space.

Even then, just reaching that die size is a compromise between features and production costs. AMD didn’t simply settle for a larger GPU, but they had to give up some things to keep it from being even larger. SIMDs were on the chopping block; 32nm Cayman would have had more SIMDs for more performance. Features were also lost, and this is where AMD is keeping mum. We know PCI Express 3.0 functionality was scheduled for the 32nm part, where AMD had to give up their PCIe 3.0 controller for a smaller 2.1 controller to make up for their die size difference. This in all honesty may have worked out better for them: PCIe 3.0 ended up being delayed until November, so suitable motherboards are still at least months away.

The end result is that Cayman as we know it is a compromise to make it happen on 40nm. AMD got their new VLIW4 architecture, but they had to give up performance and an unknown number of features to get there. On the flip side this will make 28nm all the more interesting, as we’ll get to see many of the features that were supposed to make it for 2010 but never arrived.

Refresher: The 6800 Series’ New Features VLIW4: Finding the Balance Between TLP, ILP, and Everything Else
POST A COMMENT

167 Comments

View All Comments

  • AnnihilatorX - Thursday, December 16, 2010 - link

    I disagree with you rarson

    This is what sets Anandtech apart, it has quality over quantity.
    Anandtech is the ONLY review site which offers me comprehensive information on the architecture, with helpful notes on the expected future gaming performance. It mention AMD intended the 69xx to run on 35nm, and made sacrifices. If you go to Guru3D''s review, the editor in the conclusion stated that he doesn't know why the performance lacks the wow factor. Anandtech answered that question with the process node.

    If you want to read reviews only, go onto google and search for 6850 review, or go to DailyTech's daily recent hardware review post, you can find over 15 plain reviews. Even easier, just use the Quick Navigation menu or the Table of Content in the freaking first page of article. This laziness does not entrice sypathy.
    Reply
  • Quidam67 - Thursday, December 16, 2010 - link

    Rarson's comments may have been a little condescending in their tone, but I think the critism was actually constructive in nature.

    You can argue the toss about whether the architecture should be in a separate article or not, but personally speaking, I actually would prefer it was broken out. I mean, for those who are interested, simply provide a hyper-link, that way everyone gets what they want.

    In my view, a review is a review and an analysis on architecture can compliment that review but should not actually a part of the review itself. A number of other sites follow this formula, and provide both, but don't merge them together as one super-article, and there are other benefits to this if you read on.

    The issue of spelling anf grammer is trivial, but in fact could be symptomatic of a more serious problem, such as the sheer volume of work Ryan has to perform in the time-frame provided, and the level of QA being squeesed in with it. Given the nature of NDA's, perhaps it might take the pressure off if the review did come first, and the architecture second, so the time-pressures weren't quite so restrictive.

    Lastly, employing a professional proof-reader is hardly an insult to the original author. It's no different than being a software engineer (which I am) and being backed up by a team of quality test analysts. It certainly makes you sleep better when stuff goes into production. Why should Ryan shoulder all the responsibility?
    Reply
  • silverblue - Thursday, December 16, 2010 - link

    I do hope you're joking. :) (can't tell at this early time) Reply
  • Arnulf - Thursday, December 16, 2010 - link

    "... unlike Turbo which is a positive feedback mechanism."

    Turbo is a negative feedback mechanism. If it was a positive feedback mechanism (= a consequence of an action resulting in further action in same direction) the CPU would probably burn up almost instantly after Turbo triggered as its clock would increase indefinitely, ever more following each increase, the higher the temperature, the higher the frequency. This is not how Turbo works.

    Negative feedback mechanism is a result of an action resulting in reaction (= action in the opposite direction). In the case of CPUs and Turbo it's this to temperature reaction that keeps CPU frequency under control. The higher the temperature, the lower the frequency. This is how Turbo and PowerTune work.

    The fact that Turbo starts at lower frequency and ramps it up and that PowerTune starts at higher frequency and brings it down has no bearing on whether the mechanism of control is called "positive" or "negative" feedback.

    Considering your fondness for Wikipedia (as displayed by the reference in the article) you might want to check out these:

    http://en.wikipedia.org/wiki/Negative_feedback
    http://en.wikipedia.org/wiki/Positive_feedback

    and more specifically:

    http://en.wikipedia.org/wiki/Negative_feedback#Con...
    Reply
  • Ryan Smith - Thursday, December 16, 2010 - link

    Hi Arnulf;

    Fundamentally you're right, so I won't knock you. I guess you could say I'm going for a very loose interpretation there. The point I'm trying to get across is that Turbo provides a performance floor, while PowerTune is a performance ceiling. People like getting extra performance for "free" more than they like "losing" performance. Hence one experience is positive and one is negative.

    I think in retrospect I should have used positive/negative reinforcement instead of feedback.
    Reply
  • Soda - Thursday, December 16, 2010 - link

    Anyone noticed that the edge missing og the boards 8-pin power connector ?

    Apparently the AMD made a mistake in the reference design of the board and didn't calculating the space needed by the cooler.

    If you look closely on the power connector in http://images.anandtech.com/doci/4061/6970Open.jpg you'll notice the missing edge.

    For a full story on the matter you can go to http://www.hardwareonline.dk/nyheder.aspx?nid=1060...
    For the english speaking people I suggest the googlish version here http://translate.google.com/translate?hl=da&sl...

    There are some pictures to backup the claim the mistake made AMD here.

    Though it haven't been confirmed by AMD if this is only a mistake on the review boards or all cards of the 69xx series.
    Reply
  • versesuvius - Thursday, December 16, 2010 - link

    I have a 3870, on a 17 inch monitor, and everything is fine as long as games go. The hard disk gets in the way sometimes, but that is just about it. All the games run fine. No problem at all. Oh, there's more: They run better on the lousy XBOX. Why the new GPU then? Giant monitors? Three of them? Six of them? (The most fun I had on Anandtech was looking at pictures of AT people trying to stabilize them on a wall). Oh, the "Compute GPU"? Wouldn't that fit on a small PCI card, and act like the old 486 coprecessor, for those who have some use for it? Or is it just a silly excuse for not doing much at all, or rather not giving much to the customers, and still charge the same? The "High End"! In an ideal world the prices of things go down, and more and more people can afford them. That lovely capitalist idea was turned on its head, sometime in the eighties of the last century, and instead the notion of value was reinvented. You get more value, for the same price. You still have to pay $400 for your graphic card, even though you do not need the "Compute GPU", and you do not need the aliased superduper antialiasing that nobody yet knows how to achieve in software. Can we have a cheap 4870? No that is discontinued. The 58 series? Discontinued. There are hundreds of thousands or to be sure, millions of people who will pay 50 dollars for one. All ATI or Nvidia need to do is to fine tune the drivers and reduce power consumption. Then again, that must be another "High End" story. In fact the only tale that is being told and retold is "High End"s and "Fool"s, (i.e. "We can do whatever we want with the money that you don't have".) Until better, saner times. For now, long live the console. I am going to buy one, instead of this stupid monstrosity and its equally stupid competitive monstrosity. Cheaper, and gets the job done in more than one way.

    End of Rant.
    God Bless.
    Reply
  • Necc - Thursday, December 16, 2010 - link

    So True. Reply
  • Ananke - Thursday, December 16, 2010 - link

    Agree. I have 5850 and it does work fine, and I got it on day one at huge discount, but still - it is kind of worthless. Our entertainment comes more exclusively from consoles, and I discrete high end card that commands above $100 price tag is worthless. It is nice touch, but I have no application for it in everyday life, and several months later is already outdated or discontinued.

    My guess, integrated in the CPU graphics will take over, and the mass market discrete cards will have the fate of the dinosaurs very soon.
    Reply
  • Quidam67 - Thursday, December 16, 2010 - link

    Wonderfully subversive commentary. Loved it.

    Still, the thing I like about the High end (I'll never buy it until my Mortgage is done with) is that it filters down to the middle/low end.

    Yes, lots of discontinued product lines but for example, I thought the HD5770 was a fantastic product. Gave ample performance for maintstream gamers in a small form-factor (you can even get it in single slot) with low heat and power requirements meaning it was a true drop-in upgrade to your existing rig, with a practical upgrade path to Crossfire X.

    As for the xbox, that hardware is so outdated now that even the magic of software optimisation (a seemingly lost art in the world of PC's) cannot disguise the fact that new games are not going to look any better, or run any faster, than those that came out at launch. Was watching GT5 in demo the other day and with all the hype about how realistic it looks (and plays) I really couldn't get past the massive amount of Jaggies on screen. Also, very limited damage modelling, and in my view that's a nod towards hardware limitations rather than a game-design consideration.
    Reply

Log in

Don't have an account? Sign up now