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Report: AMD's Tonga-XT GPU To Have 384-Bit Memory Bus

By - Source: PC Watch | B 29 comments

Might AMD's next Tonga-based graphics card come with a 384-bit memory interface?

When the AMD Radeon R9 285 arrived, one of the first thoughts that most of us had was whether AMD would also be building a Tonga-based graphics card with more stream processors. Not too much is known about the so-called R9 285X, and although we have been able to speculate, it's not up until now that some concrete potential information has surfaced. Japanese website PCWatch has posted some details of the fully-enabled Tonga GPU along with a block diagram.

According to the report, a fully-enabled Tonga GPU, which we expect to be called the Tonga XT, carries 2048 stream processors, 128 TMUs and 32 or 48 ROPs, along with two additional 64-bit memory controllers over the Tonga-Pro on the R9 285, giving it a 384-bit memory interface. This suggests that a graphics card featuring the GPU would come with 3 GB of GDDR5 memory.Image Source: PC WatchImage Source: PC Watch

That's where the details end. Unfortunately, we still haven't heard anything official about the R9 285X, nor a second graphics card with a Tonga GPU for that matter, so for the time being all we know is that this rumor says that the fully-enabled Tonga GPU carries 2048 SPs and a 384-bit memory interface. Whether a graphics card with said GPU will be built, or what it will be officially called, remains a mystery.

If AMD does build this graphics card, we would expect it to perform a notch above the Radeon R9 280X (just like the R9 285 performed a notch above the R9 280), while operating at a slightly lower TDP than the R9 280X. That said, we can't be sure about this, as the bigger memory interface might just make the card powerful enough to compete with Nvidia's just-announced GTX 970, so let's not get our hopes up.

Follow Niels Broekhuijsen @NBroekhuijsen. Follow us @tomshardware, on Facebook and on Google+.

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  • 0 Hide
    pacdrum_88 , September 30, 2014 10:24 AM
    AMD has come catching up to do if they're going to be able to compete with Nvidia on the level of the 970 and 980. I've always been an AMD guy, but unless they really get their power usage down and ramp up the performance, things aren't looking so good. If the 285 is what we have to look forward to (Reasonably less power usage but not much performance gained) then I see the future weighing heavily in team green's favor.
  • 4 Hide
    Sakkura , September 30, 2014 11:57 AM
    Quote:
    This is particularly interesting because it doesn't often happen that we see GPUs with memory controllers disabled, while disabling sets of shaders is a common practice to facilitate the binning process.

    Except for the GTX 660 Ti, which was GK104 cut down from 256-bit to 192-bit. And the GTX 650 Ti, which was GK106 cut down from 192-bit to 128-bit. And the GTX 570, which was GF110 cut down from 384-bit to 320-bit. And the GTX 560 SE and GTX 555, which were GF114 cut down from 256-bit to 192-bit. And the GTX 470, and the GTX 465, and the GTX 275, and so on...
  • 1 Hide
    kinggremlin , September 30, 2014 2:28 PM
    Quote:
    , it's not up until now that some concrete potential information


    Concrete potential? Isn't that an oxymoron?
  • Add your comment Display all 29 comments.
  • 1 Hide
    spentshells , September 30, 2014 5:19 PM
    Quote:
    AMD has come catching up to do if they're going to be able to compete with Nvidia on the level of the 970 and 980. I've always been an AMD guy, but unless they really get their power usage down and ramp up the performance, things aren't looking so good. If the 285 is what we have to look forward to (Reasonably less power usage but not much performance gained) then I see the future weighing heavily in team green's favor.


    This will compete with the 970 and that's the point, Notice the 285 vs the 7950 the bus width is slower yet it performs slightly above at stock, those same revisions will go into this core and it will be matched with the additional bus width and shader count which will show well at least beating the 780 while bringing down the power. If they keep it cheaper than the 780 thats how they sell cards. I see this happening or at meeting the 780 but later we will see an xtx version of the tonga core almost like a Ghz card which will at the very least beat and get close to the 970. Likely at a cheaper price than at least the 780.
  • 0 Hide
    Sakkura , September 30, 2014 6:34 PM
    Quote:
    This will compete with the 970 and that's the point, Notice the 285 vs the 7950 the bus width is slower yet it performs slightly above at stock, those same revisions will go into this core and it will be matched with the additional bus width and shader count which will show well at least beating the 780 while bringing down the power. If they keep it cheaper than the 780 thats how they sell cards. I see this happening or at meeting the 780 but later we will see an xtx version of the tonga core almost like a Ghz card which will at the very least beat and get close to the 970. Likely at a cheaper price than at least the 780.


    The GTX 780 is being phased out, the 970 is what AMD will be competing with going forward.

    Adding in the remaining shaders for an R9 285X is not going to make it as powerful as the 780, let alone the 970. The 285 is barely ahead of the 280, there's no reason to think the 285X will be much faster than the 280X.

    And I really don't see them adding another version of Tonga later on to reach even higher performance levels. They have Hawaii covering the high-end market, Tonga is basically just a smaller version of Hawaii.
  • 0 Hide
    fuzzion , September 30, 2014 7:35 PM
    So my 780ti is still cutting edge.
  • 0 Hide
    alextheblue , September 30, 2014 7:40 PM
    Well Sakkura you have to look at it this way... the 285 is a smidge faster than the 280 despite having a narrower 256-bit bus and far less memory bandwidth. This is lately thanks to serious compression improvements. So IF the 285X has a full 384-bit bus, it will have roughly the same bandwidth as the 280X, but would still have the improved compression that saved the 285. The potential for big performance increases above the 280X is there.

    However, I personally don't put much stock in this rumor. We'll see, though.
  • 0 Hide
    spentshells , September 30, 2014 9:07 PM
    Quote:
    Quote:
    This will compete with the 970 and that's the point, Notice the 285 vs the 7950 the bus width is slower yet it performs slightly above at stock, those same revisions will go into this core and it will be matched with the additional bus width and shader count which will show well at least beating the 780 while bringing down the power. If they keep it cheaper than the 780 thats how they sell cards. I see this happening or at meeting the 780 but later we will see an xtx version of the tonga core almost like a Ghz card which will at the very least beat and get close to the 970. Likely at a cheaper price than at least the 780.


    The GTX 780 is being phased out, the 970 is what AMD will be competing with going forward.

    Adding in the remaining shaders for an R9 285X is not going to make it as powerful as the 780, let alone the 970. The 285 is barely ahead of the 280, there's no reason to think the 285X will be much faster than the 280X.

    And I really don't see them adding another version of Tonga later on to reach even higher performance levels. They have Hawaii covering the high-end market, Tonga is basically just a smaller version of Hawaii.


    But it will also get the far larger memory bus and when paired with the revised core and a possible overclock we could see a huge boost. Purely speculation. Interestingly 285 did so well with the 256bit bus.

    I want a 970 in the future but I could be swayed back to AMD with performance with the right price.
  • 0 Hide
    N.Broekhuijsen , September 30, 2014 10:23 PM
    Quote:
    Except for the GTX 660 Ti, which was GK104 cut down from 256-bit to 192-bit. And the GTX 650 Ti, which was GK106 cut down from 192-bit to 128-bit. And the GTX 570, which was GF110 cut down from 384-bit to 320-bit. And the GTX 560 SE and GTX 555, which were GF114 cut down from 256-bit to 192-bit. And the GTX 470, and the GTX 465, and the GTX 275, and so on...
    Whoops. But all fixed now.

  • 0 Hide
    somebodyspecial , September 30, 2014 10:35 PM
    Unfortunately NV can hit 1.5ghz on OC, so no chance of catching the 15-20% free if someone wants it and even then power wasn't through the roof. So yeah, AMD has a lot of catching up to do. You won't hit 1.5ghz on tonga without some pretty special cooling I'd guess. NV's chip did it at quite a few places with nothing special and not much voltage to play with on the users part. It would seem AMD's only option here is hacking pricing to stay competitive and that just means another quarterly loss most likely which is definitely bad for a company who is far in debt, and very little cash to fight with. Their R&D dropping over the last 4yrs shows this also. NV now spends more and doesn't make many of the things AMD does (cpus for servers, consoles etc).

    When your enemy outspends you, makes 3-5x more profit per year or quarter, and makes less products, you're in serious trouble. Tonga and maxwell show this R&D spending clearly (same with Intel cpus and R&D - we're about to see the same thing happen in gpus, which sucks).
  • 0 Hide
    erendofe , September 30, 2014 11:44 PM
    AMD will have a little (I do mean little) breathing room for a short time. a lot of people aren't to likely to shell out upwards of a grand on a card. but they will need to put some sort of answer out to the 980 and 970 I think
  • 0 Hide
    sp00 , October 1, 2014 12:41 AM
    they only need an answer for the 970. Not a lot of people are going to spend $500 for a 980.
  • 1 Hide
    Sakkura , October 1, 2014 3:27 AM
    Quote:
    Well Sakkura you have to look at it this way... the 285 is a smidge faster than the 280 despite having a narrower 256-bit bus and far less memory bandwidth. This is lately thanks to serious compression improvements. So IF the 285X has a full 384-bit bus, it will have roughly the same bandwidth as the 280X, but would still have the improved compression that saved the 285. The potential for big performance increases above the 280X is there.

    However, I personally don't put much stock in this rumor. We'll see, though.


    Quote:
    But it will also get the far larger memory bus and when paired with the revised core and a possible overclock we could see a huge boost. Purely speculation. Interestingly 285 did so well with the 256bit bus.

    I want a 970 in the future but I could be swayed back to AMD with performance with the right price.


    The thing you guys are forgetting is that the R9 285 is not bandwidth-starved. Extra memory bandwidth only helps performance when the GPU actually needs more bandwidth. The Tonga GPU is only a slightly tweaked successor to Tahiti, so there obviously isn't a ton of extra performance to be had. Lower power consumption does, however, lead to higher power efficiency, which is always nice.

    Heck, remember the 7870 XT? That was Tahiti on a 256-bit memory interface, and even that didn't really hurt performance. Tom's Hardware looked into that in this article. Select quote:

    Quote:
    It’s plain to see that the smaller memory interface doesn’t really impact performance.

  • 0 Hide
    heero yuy , October 1, 2014 10:03 AM
    AMD has come catching up to do if they're going to be able to compete with Nvidia on the level of the 970 and 980. I've always been an AMD guy, but unless they really get their power usage down and ramp up the performance, things aren't looking so good. If the 285 is what we have to look forward to (Reasonably less power usage but not much performance gained) then I see the future weighing heavily in team green's favor.

    AMD needs to catch up? AMDs next cards are going to have the HBM 3D memory stuff NVidia isnt going to have that untill 2016 (their version (HBC) apparently fell flat on its face so they are having to use what AMD have made granted they will be using the second generation by that point but so will AMD but for now AMD have 1st gen HBM thats faster than the GDDR5 that NVidia is currently using)
  • 0 Hide
    Swede69 , October 1, 2014 10:19 AM
    AMD is sooooo far behind in both cpu and gpu performance compared to Intel/Nvidia, I don't even know why they try at this point. I mean the 970 beats the 290 and it cost $150 less!
  • 0 Hide
    spentshells , October 1, 2014 10:30 AM
    Im not so sure Sakura, the 285x does have a third more shaders also the tonga chip was by default clocked a bit lower as they didn't want to displace the 280x quite yet. Also the 256bit mem bus was fast enough because it was only addressing 2GB of ram and and a chopped down tahiti chip with lowered clocks.(7870LE) The 285 was not starved apparently due to changes to the core. I'm obviously speculating but it would be nice to see this new card land right where the 280(x) is priced and perform at around the 780, so it could at least compete with the 970 offering a better price.
  • 0 Hide
    heero yuy , October 1, 2014 2:18 PM
    Nvidia is not going to have HBM memory untill 2016 AMD will have if January - February next year

    and you are comparing apples to oranges the 290 is the "last generation" of graphics cards the 970 is the "current" or "next" generation


    quote system is borked i clicked the add quote thing on Swede69s comment and it didnt happen :/ 
  • 0 Hide
    Sakkura , October 2, 2014 4:21 AM
    Quote:
    Im not so sure Sakura, the 285x does have a third more shaders also the tonga chip was by default clocked a bit lower as they didn't want to displace the 280x quite yet. Also the 256bit mem bus was fast enough because it was only addressing 2GB of ram and and a chopped down tahiti chip with lowered clocks.(7870LE) The 285 was not starved apparently due to changes to the core. I'm obviously speculating but it would be nice to see this new card land right where the 280(x) is priced and perform at around the 780, so it could at least compete with the 970 offering a better price.

    The 285X does not have a third more shaders. The Tonga GPU only has 2048 shaders, which in the 285 is cut down by one eighth to 1792. Which means the 285X can at most have one seventh more shaders than the 285.

    It would be nice to see the 285X land at the pricing of the 280X and perform like the 780, but it's extremely unlikely. Remember, the 285X uses exactly the same architecture and configuration as the R9 290 and 290X, just with fewer resources. So performance is certainly going to be well behind the 290, and by extension the 780 as well.
  • 0 Hide
    somebodyspecial , October 2, 2014 6:03 AM
    Quote:
    AMD has come catching up to do if they're going to be able to compete with Nvidia on the level of the 970 and 980. I've always been an AMD guy, but unless they really get their power usage down and ramp up the performance, things aren't looking so good. If the 285 is what we have to look forward to (Reasonably less power usage but not much performance gained) then I see the future weighing heavily in team green's favor.

    AMD needs to catch up? AMDs next cards are going to have the HBM 3D memory stuff NVidia isnt going to have that untill 2016 (their version (HBC) apparently fell flat on its face so they are having to use what AMD have made granted they will be using the second generation by that point but so will AMD but for now AMD have 1st gen HBM thats faster than the GDDR5 that NVidia is currently using)


    ok, 1st, please give links to proof or article about AMD's next chips and when they arrive. AFAIK nobody knows what is on the next stuff, nor when the 20nm is arriving (soon is about the best you'll get).

    2nd, proof extra memory speed/bandwidth will do anything for chips that so far seem not so starved on this front. I believe this is why NV is waiting a little longer. It isn't needed. IF you put 10ghz memory on todays cards (doesn't exist but makes the point) you'd get nothing in return except (most likely) some really expensive cards...LOL. Note both maxwells (900 series) have been dropped to 256bit and didn't hurt a thing. New tricks (IE, compression etc) keep allowing them to get more from the same memory tech. Unless NV's gpus for the 20nm shrink are so super fantastic they require this 3d stuff, I'd guess all that is needed is a move BACK to 384bit memory interface (or heck 512 can be done also) and call it a day. Unless the new tech is the same price (highly doubt this), you should stick to mainstream stuff to allow the costs to stay lower for customers, not to mention this usually helps volume production also (again helping costs, since this stuff is widely available usually). When you shoot for the latest stuff it had better REALLY be worth it, or volume production sucks and prices skyrocket usually.

    NV's 970/980 are 224GB/s vs. 780ti's 336! Yet, 780ti isn't massively faster even with the massive bandwidth haircut (rather 980 is faster, so quite amazing feat). See the point? NV obviously has at least another 112GB/s to play with just upping again to 384bit. Again, they can jump to 512bit also and at another die shrink mem surely speeds up too giving even higher numbers above 1750mhz we are running on 970/980. If AMD moves to a newer memory and it's more expensive or hard to get volume of, they are making a huge mistake and it will cost them vs. a cheaper more readily available memory NV will use that is more than enough bandwidth to be effective.

    Again, tons of bandwidth does just about nothing if you don't have a gpu to use it. It would be different if you got 30% perf increase just from say OCing the memory on a 980, but it all comes from the gpu side instead (the 15-20% when sites OCed it to 1.5ghz shows it's coming from the gpu clocks not much from mem). So I fail to see how this will help AMD much. NV isn't bandwidth starved now, 20nm won't make it so and they can just go back to 384bit etc.

    http://wccftech.com/amd-20nm-r9-390x-feautres-20nm-hbm-9x-faster-than-gddr5/
    380x competing against 980, while 390x will compete vs 980ti. I don't see any real gains here. NV will just answer with their own 20nm versions and laugh (which is what 380x/390x are, 20nm). If Bermuda really requires water out of the box, color me unimpressed.

    Unfortunately AMD has to do something to compete for xmas, not next year:
    http://wccftech.com/amd-radeon-r9-390x-arrives-1h-2015-feature-hydra-liquid-cooling/
    "And AMD will have to address the market now. According to digitimes and several other sources, AMD will be introducing some very aggressive price cuts on its R9 290 series. My own personal sources have also told me that AMD will very likely be introducing more big name video game titles to their never settle bundle program. "

    Say goodbye to any profits, this will merely stop xmas bleeding but at the same time kills profits if any could have been had to begin with vs. NV's current stuff. At some point you need to make MONEY, not price cut and add games to compete. That requires a BETTER GPU, not faster memory that can't save them. It would appear Fiji and Bermuda won't change much if AMD's aiming their die shrinks at TODAY's NV gpus instead of NV's 20nm versions. Yet again, I see NV's R&D winning and AMD financials taking another hit for quite some time, but the quarterly reports will tell all after xmas in Jan/Feb.
  • 0 Hide
    somebodyspecial , October 2, 2014 6:21 AM
    Note in the article I linked it's a LEAK and still just a RUMOR (and not coming early next year if true - what does "EARLY" mean? Probably the same timeframe as NV's 20nm answers). But even if it pans out as shown bandwidth won't change the game (not for 20nm gen anyway), they need a better GPU to do that.

    Edit:
    http://www.tweaktown.com/news/40339/amd-to-release-its-radeon-r9-390x-early-next-year-20nm-with-hbm-tech/index.html
    Tweaktown says 1st half next year, so this thing could be 6-8 months away. You say 1st Q when it lands before April 1st don't you? That means AMD has to hack pricing and add free games for 5 months+, that will kill the next two quarters of profits.
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