A Bit More On Graphics Core Next 1.1

With the launch of Hawaii, AMD is finally opening up a bit more on what Graphics Core Next 1.1 entails. No, they still aren’t giving us an official name – most references to GCN 1.1 are noting that 290X (Hawaii) and 260X (Bonaire) are part of the same IP pool – but now that AMD is in a position where they have their new flagship out they’re at least willing to discuss the official feature set.

So what does it mean to be Graphics Core Next 1.1? As it turns out, the leaked “AMD Sea Islands Instruction Set Architecture” from February appears to be spot on. Naming issues with Sea Islands aside, everything AMD has discussed as being new architecture features in Hawaii (and therefore also in Bonaire) previously showed up in that document.

As such the bulk of the changes that come with GCN 1.1 are compute oriented, and clearly are intended to play into AMD’s plans for HSA by adding features that are especially useful for the style of heterogeneous computing AMD is shooting for.

The biggest change here is support for flat (generic) addressing support, which will be critical to enabling effective use of pointers within a heterogeneous compute context. Coupled with that is a subtle change to how the ACEs (compute queues) work, allowing GPUs to have more ACEs and more queues in each ACE, versus the hard limit of 2 we’ve seen in Southern Islands. The number of ACEs is not fixed – Hawaii has 8 while Bonaire only has 2 – but it means it can be scaled up for higher-end GPUs, console APUs, etc. Finally GCN 1.1 also introduces some new instructions, including a Masked Quad Sum of Absolute Differences (MQSAD) and some FP64 floor/ceiling/truncation vector functions.

Along with these architectural changes, there are a couple of other hardware features that at this time we feel are best lumped under the GCN 1.1 banner when talking about PC GPUs, as GCN 1.1 parts were the first parts to introduce this features and every GCN 1.1 part (at least thus) far has that feature. AMD’s TrueAudio would be a prime example of this, as both Hawaii and Bonaire have integrated TrueAudio hardware, with AMD setting clear expectations that we should also see TrueAudio on future GPUs and future APUs.

AMD’s Crossfire XDMA engine is another feature that is best lumped under the GCN 1.1 banner. We’ll get to the full details of its operation in a bit, but the important part is that it’s a hardware level change (specifically an addition to their display controller functionality) that’s once again present in Hawaii and Bonaire, although only Hawaii is making full use of it at this time.

Finally we’d also roll AMD’s power management changes into the general GCN 1.1 family, again for the basic reasons listed above. AMD’s new Serial VID interface (SIV2), necessary for the large number of power states Hawaii and Bonaire support and the fast switching between them, is something that only shows up starting with GCN 1.1. AMD has implemented power management a bit differently in each product from an end user perspective – Bonaire parts have the states but lack the fine grained throttling controls that Hawaii introduces – but the underlying hardware is identical.

With that in mind, that’s a short but essential summary of what’s new with GCN 1.1. As we noted way back when Bonaire launched as the 7790, the underlying architecture isn’t going through any massive changes, and as such the differences are of primarily of interest to programmers more than end users. But they are distinct differences that will play an important role as AMD gears up to launch HSA next year. Consequently what limited fracturing there is between GCN 1.0 and GCN 1.1 is primarily due to the ancillary features, which unlike the core architectural changes are going to be of importance to end users. The addition of XDMA, TrueAudio, and improved power management (SIV2) are all small features on their own, but they are features that make GCN 1.1 a more capable, more reliable, and more feature-filled design than GCN 1.0.

The AMD Radeon R9 290X Review Hawaii: Tahiti Refined
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  • Blamcore - Friday, October 25, 2013 - link

    Wow, I was just remarking yesterday that NV fanbois had sunk to the level of apple fanbois, when I was seeing the argument "you just like AMD because you can't afford NV" on a few boards. Now here is apple fanbois famous argument "my company is better because they have a higher profit margin" Gratz your unreasonable bias just went up a level!
    I know, you aren't a fanboy, you are really a business expert here to recommend that a company should gain market share by releasing a card roughly equal to what it's competitor had out for months and pricing it the same as they do! Maybe the could have asked 650 if they released it last January
    Reply
  • puppies - Saturday, October 26, 2013 - link

    R+D costs come from the sale price of the card. Are you tring to claim a $300 GPU costs $300 in materials? R+D costs also come from the fact that shrinking the process enables the manufacturer to get more cards per die each time.

    Look at Intel and AMD their chips don't go up in price each time they get faster, they stay at the same price point. The last 2 cards I have bought have been Nvidia but the next one will be AMD at this rate. I expect a 660TI to be faster and more energy efficient than a 560TI and at the same price point WHEN IT IS RELEASED and I think a lot of people are in the same boat. Nvidia is trying to push people into spending more each time they release a new model line up and it stinks.

    I don't care if a 660 is faster than a 560TI, forcing people to move down the GPU lineup just smacks of NVIDIA price gouging.
    Reply
  • Samus - Thursday, October 24, 2013 - link

    I have to disagree with you Berzerker. Although his post clearly "overpromotes" the 290, it is incredible value when you consider it is faster and cheaper (by hundreds of dollars) than the Titan.

    -Geforce 660TI owner
    Reply
  • Laststop311 - Thursday, October 24, 2013 - link

    For people that value a quiet computer, this card is trash Reply
  • Spunjji - Friday, October 25, 2013 - link

    For people that value a quiet computer, all stock coolers are useless.

    People that value a truly quiet computer won't even be playing at this end of the GPU market.
    Reply
  • Samus - Friday, October 25, 2013 - link

    This card is a great candidate for water cooling since the back of the PCB is essentially empty. Water cooling the face side is cheaper/easier, and this card can clearly use it. Reply
  • HisDivineOrder - Friday, October 25, 2013 - link

    He didn't say "silent." He said "quiet." I'd argue the Titan/780/690 coolers were all "quiet," but not "silent."

    Since he said quiet, I don't think his expectation is unreasonable to expect a certain level of "quiet" at the $500+ range of discrete cards.
    Reply
  • Nenad - Friday, October 25, 2013 - link

    780 with stock cooler is not useless, and it IS quiet (it is not 'silent')
    BTW, going by posted numbers it seems 290x will be TWICE as noisy as GTX780 ?
    Reply
  • ballfeeler - Thursday, October 24, 2013 - link

    Methinks Berzerker7 is just salty and perhaps partial to nvidia.  Nothing itchy wrote is inaccurate, including the $550 price that Salty-Berzerker7 claimed was $600. 

    -          Fastest card ?  - yup

    -          Free game ? – yup

    -          Pooped all over titan ? –yup

    Do not be salty mr. Berzerker7.  AMD just roundhouse kicked nvidia square in the gonads with performance above Titan for half the price.
    Reply
  • Shark321 - Thursday, October 24, 2013 - link

    At 1080p it's actually slower than Titan if you average all reviews across the sites. With some reviews even slightly slower than the 780. It's also the loudest card ever produced after 30 minutes of playing (9,6 Sone in Battlefield 3 according to PCGamesExtreme). With this noise it's not acceptable and there will be no other coolers for the time being. Reply

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