Bonaire’s Microarchitecture - What We’re Calling GCN 1.1

With our introduction out of the way, before looking at the cards and our performance results we would like to dive into a technical discussion and a bit of nitpicking. Specifically we would like to spend some time talking about architectures and product naming, as it’s going to be a bit confusing at first. As AMD has stated numerous times in the past, Graphics Core Next is a long-term architecture for the company. AMD intends to evolve GCN over the years, releasing multiple microarchitectures based on GCN that improve the architecture and add features while still being rooted in the design principles of GCN. GCN is after all the other half of AMD’s upcoming HSA-capable APUs, the culmination of years of AMD’s efforts with HSA/Fusion.

So where does Bonaire fit in? Bonaire is of course a GCN part; it’s a new microarchitecture that’s technically different from Southern Islands, but on the whole it’s a microarchitecture that’s extremely close in design to Southern Islands. In this new microarchitecture there are some changes – among other things the new microarchitecture implements some new instructions that will be useful for HSA, support for a larger number of compute work queues (also good for HSA) and it also implements a new version of AMD’s PowerTune technology (which we’ll get to in a bit) – but otherwise the differences from Southern Islands are very few. There are no notable changes in shader/CU efficiency, ROP efficiency, graphics features, etc. Unless you’re writing compute code for AMD GPUs, from what we know about this microarchitecture it’s likely you’d never notice a difference.

Unfortunately AMD has chosen to more-or-less gloss over the microarchitectural differences altogether, which is not wholly surprising since they will be selling Bonaire and previous generation products side-by-side. Bonaire’s microarchitecture has no official name (at least not one AMD wants to give us) and no version number. The Sea Islands name we’ve been seeing thrown around is not the microarchitecture name. Sea Islands is in fact the name for all of the GPUs in this wave – or perhaps it would be better to say all of the products created in this development cycle – including both Bonaire and it’s new microarchitecture, and Oland, AMD’s other new GPU primarily for mobile that is purely Southern Islands in microarchitecture.

In fact if not for the fact that AMD released (and then retracted) an ISA document called “AMD Sea Islands Instruction Set Architecture” last month, we would likely know even less about Bonaire’s microarchitecture. The document has been retracted at least in part due to the name (since AMD will not be calling the microarchitecture Sea Islands after all), so as a whole AMD isn’t particularly keen in talking about their microarchitecture at this time. But at the same time from a product standpoint it gives you an idea of how AMD is intending to smoothly offer both Southern Islands and Bonaire microarchitecture parts together as one product family.

Anyhow, for the sake of our sanity and for our discussions, in lieu of an official name from AMD we’re going to be retroactively renaming AMD’s GCN microarchitectures in order to quickly tell them apart. For the rest of this article and in future articles we will be referring to Southern Islands as GCN 1.0, while Bonaire’s microarchitecture will be GCN 1.1, to reflect the small changes between it and the first rendition of GCN.

Ultimately the differences between GCN 1.0 and GCN 1.1 are extremely minor, but they are real. But despite our general annoyance in how this has been handled, for consumers the difference between a GCN 1.0 card like the 7770 and a GCN 1.1 card like the 7790 should be limited to their innate performance differences, and of course PowerTune. GCN 1.1 or not, Bonaire fits in nicely in AMD’s current product stack and is in a position where it’s reasonable for it to be lumped together with GCN 1.0 parts as a single family. It’s really only the technical enthusiasts (like ourselves) and programmers that should have any significant reason to care about GCN 1.0 versus GCN 1.1. For everyone else this may just as well be another Southern Islands part.

Introduction The New PowerTune: Adding Further States
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  • silverblue - Friday, March 22, 2013 - link

    You must've missed the part about them simply not having as much time to test the 7790 as they'd have liked because they were at GTC. Other sites apologised for their lack of time as well.

    There's a whole load of other reviews out there; only a few have overclocking results (Guru3D notably), and as far as I can see only AT, of the major sites, has both the 7790 and a factory overclocked 7790 in the same test. Guru3D is alone in providing a CrossFire test and though two 7790s perform about the same as a sole 670, there's no power readings. There's a good number of different titles being benchmarked so it's not strictly a list of AMD-says-test-these-titles, plus Tomb Raider, a Gaming Evolved title, performs better on NVIDIA hardware. There's a few bugs with the beta drivers used for the 7790 in these reviews most notably with latencies (a bug that has already been fixed with the next Catalyst release so yes, we will see new drivers soon), however the latency values are so far ahead on average of what we used to see from AMD that this can hardly be classed as an issue. Testing has generally centred on 1920x1080 because that's really the limit where cards like this are supposed to be performing - there's little point in 1024x768 and an equal measure of futility trying for 5760x1080 or whatever; the former is ridiculously low res and the latter is ridiculously ambitious even for a 7970 or 670/680.

    Sapphire's blurb about multi-monitor usage via the TweakTown website:

    "Working or gaming with multiple monitors is becoming increasingly popular, and the SAPPHIRE HD 7700 series supports this with AMD Eyefinity, now in its second generation. The SAPPHIRE HD 7790 OC Edition has two DVI ports (DVI-I and DVI-D), HDMI and a single DisplayPort output, supporting up to four monitors.

    The SAPPHIRE HD 7790 OC Edition model supports the FleX feature, pioneered by SAPPHIRE, that allows three digital displays to be connected to the DVI and HDMI outputs and used in AMD Eyefinity mode without the need for an external active adapter. All four outputs can be used in AMD Eyefinity mode, but the fourth display must be a DisplayPort monitor or connected with an active adapter."

    I've heard AMD's launch date for this is today; Guru3D has the following to say:

    "But I need to add this little note alright; AMD's Never Settle Reloaded promotion continues. At participating retailers beginning 02 April, 2013, gamers will be able to receive a free copy of BioShock Infinite with a purchase of their new AMD Radeon HD 7790 graphics card. See, now that's great value. The Radeon HD 7790 series cards will be available in stores starting April 2, 2013"

    Trusting this is of some use to you...
    Reply
  • CeriseCogburn - Sunday, March 24, 2013 - link

    I've run 2 flex edition cards, you idiot.
    Have you ?
    Run any MDT nVidia galaxy cards dummy ?
    How about all dvi outs so you daon't have to have $100's of dollars of soon to die amd dangly cables ?
    Heck a friend just got ANOTHER 6870 he usually runs 4 monitors, but that could only run 2 OOB and he has loads of cables, so he had to buy another cable just to run a 3rd monitor - it took 2 weeks to arrive...
    ROFL
    AMD SUCKS with eyefinity / multiple monitors and nVidia DOES NOT - nVidia keeps the end user in mind and makes it INEXPENSIVE to set up 3 or 4 monitors !

    Amd makes it cost prohibitive.
    AMD SUCKS, they lost again, totally.
    Reply
  • geniusloci - Saturday, March 23, 2013 - link

    You are a pathetically simple little mind, aren't you? Reply
  • geniusloci - Saturday, March 23, 2013 - link

    What planet do you come from?
    This card will run 4 monitors, eyefinity has done this very well, forever. With discrete audio per monitor. Nvidia is really getting handed it's ass by AMD in this category.
    This card will spank it's nvidia competition in civ5, since civ uses opencl, and nvidia sucks at opencl (and their current cards even suck at cuda).
    Crossfire: there's a crossfire port at the top, genius. It will obviously crossfire.
    Too bad Nvidia's 2D quality and video quality is such utter shit. I might have actually used that gtx660 I bought instead of sending it back for a 7870.
    Reply
  • CeriseCogburn - Sunday, March 24, 2013 - link

    You have your display port monitor or $100 active display cable dummy ? LOL
    4 monitors MY BUTT.
    Another clueless amd fanboy.
    Reply
  • eric.zaba@gmail.com - Sunday, March 24, 2013 - link

    You obviously dont have a clear understanding of gpu tech so just stop blabbing your stupidity, even most nvidia biased people can admit Check linus tech tips , check your games they all work much better on amd with multimonitor.

    and no overclock talk maybe because AMD doesnt approve of people tampering with gpus............ and because they want it to seem so good that you dont need an overclock...... and the specific hardware partners can make different port configs so why would you say that?
    and maybe comparing ASUS 650tis to this GPU is invalid becuase you didnt specify who made it so the port config advantage is completely irrelevant.

    Amd is not bankrupt because of their GPU business. and their CPU business isnt bad i dont think that getting into the gpu and cpu of the top 3 consoles (PS4 Xbox WiiU) is so bad either. and why would game biases not be true if amds drivers and games play better on the amd based systems
    eg: Crysis 3. and saying that the civ 5 benches crashed is completely stupid because a good website like anandtech doesnt normally disregard such things. and AMD didnt pay them off if they are bankrupt right? yes it can crossfire because theres crossfire connectors on the top so maybe they assumed things would be implied for the general crowd.
    Reply
  • althaz - Friday, March 22, 2013 - link

    I think it's also worth mentioning that the 7850 is a quite excellent overclocker. At stock I think it's definitely not worth the extra $30, but once overclocking is taken into account, if you can afford the $30 you are crazy not to spend it (assuming you are comfortable with overclocking of course). Reply
  • Bob Todd - Friday, March 22, 2013 - link

    Yeah, I'm curious what the pricing will look like on these a few weeks after introduction. I picked up a 7850 (2GB MSI Twin Frozr) for $170 AR a few weeks ago to put in a HTPC, and I've seen it at that price again already. It will be interesting to see if the regular sales on 7850s decrease once the 7790 is out. Kudos to AMD for offering BioShock Infinite with this. Reply
  • Aikouka - Friday, March 22, 2013 - link

    Given we're talking about gaming cards here, I think it's worthwhile to add that only the 7800s and 7900s come with AMD's Never Settle game promotion. So, if you're interested Tomb Raider and/or Bioshock Infinite, the 7850 may have significantly more value to you. If you're not interested in them, people have been selling the coupons on eBay for about $50-60 each. Reply
  • Bob Todd - Friday, March 22, 2013 - link

    There's a small paragraph in the article explaining that this card _is_ part of the Never Settle Reloaded program. It's only getting BioShock Infinite since it sits at a lower price point, but still a nice addition. The bundles are a big part of the reason I'm curious to see how the pricing shakes out. I sold a TR/BS bundle and kept about ~$50 in my pocket after fees, so I basically got a very nice 2GB 7850 for $120. You could obviously sell the BioShock code you'd get with a 7790, but if the prices for that card stay at MSRP for too long they'll have some stiff competition from 7850s on sale. Unless of course the 7850 sales dry up since it doesn't have to cover such a large swath of AMD's lineup now price wise. Reply

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