Display Tech, Cont: Fast HDMI

Moving on from multi-monitor applications, AMD has not only been working on technologies for multi-monitor users. Southern Islands will also include some video and movie technologies that will be relevant for single and multi-monitor uses alike.

With the 6000 series AMD upgraded their DisplayPort capabilities from DP 1.1 to DP 1.2. With Southern Islands AMD will be upgrading their HDMI capabilities. Currently AMD supports a subset of the complete HDMI 1.4a specification; they can drive S3D displays (the killer feature of 1.4a), but that’s the only thing out of 1.4a they support. HDMI also introduced support for 4K x 2K displays, but both displays and devices that can drive them have been rare. As displays start to become available so too does support for them with AMD’s products.

As per the relevant specifications, both DP 1.2 and HDMI 1.4a can drive 4K x 2K displays, but with the 6000 series the hardware could only handle such a display over DP 1.2. With HDMI it was an issue of bandwidth, as HDMI is based on DVI and uses the same TMDS signaling technology. At normal speed HDMI only has as much bandwidth as single-link HDMI (~4Gbps) which is not enough to drive such a large display. DVI solved this with dual-link DVI, whereas as of HDMI 1.3 the HDMI consortium solved this by tightening their cable specifications to allow for higher clocked transmissions, from 165MHz up to 340MHz.

It’s this higher transmission speed that AMD is adding support for in Southern Islands. AMD calls this Fast HDMI technology, which as near as we can tell is not any kind of HDMI trademark but simply AMD’s branding for high speed HDMI. With Fast HDMI AMD will be able to drive 4K x 2K displays over HDMI – which looks like it will be the common connector for TVs at those high resolutions – along with being able to support 1080P S3D at higher framerates with next-generation TVs. Currently AMD’s cards and TVs alike can only handle 1080P frame packed S3D at up to 48fps (24Hz/eye), or with a bit of hacking up to 60fps (30Hz/eye), which is fine for 24fps movies but much too low for gaming. As next-generation TVs add support for 1080P frame packed S3D at 120fps (60Hz/eye) Southern Islands products will be the first AMD products able to drive them over HDMI through the use of Fast HDMI.

The only remaining questions at this point are just how high does AMD’s Fast HDMI clock (they don’t necessary have to hit 340MHz), and if AMD will add support for any other features that higher bandwidths enable. AMD says that Southern Islands supports “3GHz HDMI”, which appears to be a misnomer similar to how we commonly refer to GDDR5 by its “effective clockspeed” in GHz, even though that’s not actually how it operates. In which case with Fast HDMI AMD may be referring to the maximum throughput per channel, which at 300MHz would be 3Gbps. 300Mhz would still be enough to implement features such as Deep Color (48bpp) over most current resolutions.

Display Tech: HD3D Eyefinity, MST Hubs, & DDM Audio Video & Movies: The Video Codec Engine, UVD3, & Steady Video 2.0
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  • Ryan Smith - Thursday, December 22, 2011 - link

    Since 1920x1200 has already been commented on elsewhere I'm just going to jump right to your comment on minimum FPS.

    I completely agree, and we're trying to add it where it makes sense. A lot of benchmarks are wildly inconsistent about their minimum FPS, largely thanks to the fact that minimum FPS is an instantaneous data point. When your values vary by 20%+ per run (as minimums often do), even averaging repeated trials isn't nearly accurate enough to present meaningful results.
  • CeriseCogburn - Thursday, March 8, 2012 - link

    HardOCP shows long in game fps per second charts that show dips and bottom outs are more than one momentary lapse and often are extended time periods of lowest frame rate runs, so I have to respectfully disagree.
    Perhaps the fault is fraps can show you a single instance of lowest frame rate number, and hence it's the analysis that utterly fails - given the time constraints that were made obvious, it is also clear that the extra work it would take for an easily reasoned and reasonable result that is actually of worthy accuracy is not in the cards here.
  • thunderising - Thursday, December 22, 2011 - link

    Okay. This card has left me thrilled, but wanting for more. Why?

    Well, for example, every reviewer has hit the CCC Core and Memory Max Limits, which turns into a healthy 10-12% performance boost, all for 10W.

    What, legit reviews got it to 1165MHz core and 6550Mhz memory for a 21-24% increase in performance. Now that's HUGE!

    I think AMD could have gone for something like this with the final clocks, to squeeze out every last bit of performance from this amazing card:

    Core - 1050 MHz
    Memory - 1500 MHz (6000MHz QDR)

    This was not only easily achievable, but would have placed this card at a 8-10% increase in performance all for a mere <10W rise in Load Power.

    Hoping for AIBs like Sapphire to show their magic! HD7970 Toxic, MmmmmmM...

    Otherwise, fantastic card I say.
  • Death666Angel - Friday, December 23, 2011 - link

    Maybe they'll do a 4870/4890 thing again? Launch the HD7970 and HD7970X2 and then launch a HD7990 with higher clocks later to counter nVidia.... Who knows. :-)
  • Mishera - Sunday, December 25, 2011 - link

    They've been doing it for quite some time now. Their plan has been to release a chip balancing die size, performance, and cost. Then later to compete on high end release a dual-chip card. Anand wrote on this a while ago with the rv770 story (http://www.anandtech.com/show/2679).

    Even looking at the picture of chip sizes, the 7970 is still a reasonable size. And this really was a brilliant move as though Nvidia has half the marketshare and does make a lot of money from their cards, their design philosophy has been hurting them a lot from a business standpoint.

    On a side note, Amd really made a great choice by choosing to wait until now to push for general computing. Though that probably means more people to support development and drivers, which means more hiring which is the opposite way Amd has been going. It will be interesting to see how this dichotomy will develop in the future. But right now kudos to Amd.
  • CeriseCogburn - Thursday, March 8, 2012 - link

    Does that mean amd is abandoning gamers as we heard the scream whilst Nvidia was doing thus ?
    I don't quite get it - now what nvidia did that hurt them, is praise worthy since amd did it, finally.
    Forgive me as I scoff at the immense dichotomy...
    "Perfect ripeness at the perfect time" - sorry not buying it....
  • privatosan - Thursday, December 22, 2011 - link

    PRT is a nice feature, but there is an failure in the article:

    'For AMD’s technology each tile will be 64KB, which for an uncompressed 32bit texture would be enough room for a 4K x 4K chunk.'

    The tile would be 128 x 128 texels; 4K x 4K would be quite big for a tile.
  • futrtrubl - Thursday, December 22, 2011 - link

    I was going to comment on that too. A 4k x 4k x 32bit (4byte) texture chunk would be around 67MB uncompressed. For a 32bit texture you could only fit a 128x128 array in a 64KB chunk. An 8bit/pixel texture could be 4k*4k
  • Stonedofmoo - Thursday, December 22, 2011 - link

    Thanks for the review. A request though...
    To the hardware sites doing these reviews, many of us in this day and age run dual monitor or more. It always frustrates in me in these reviews that we get a long write up on the power saving techniques the new cards use, and never any mention of it helps those of us running more than one display.

    For those not in the know, if you run more than one display on all the current generations the cards do NOT downclock the GPU and memory nearly as much as they do on single montor configurations. This burns quite a lot more power and obviously kicks out more heat. No site ever mentions this which is odd considering so many of us have more than one display these days.

    I would happily buy the card that finally overcomes this and actually finds a way of knocking back the clocks with multi-monitor setups. Is the new Radeon 7xxx series that card?
  • Galcobar - Thursday, December 22, 2011 - link

    It's in the article, on the page entitled "Meet the Radeon 7970."

    Ryan also replied to a similar comment by quoting the paragraph addressing multi-monitor setups and power consumption at the top of page of the comments.

    That's two mentions, and the answer to your question.

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