Tuesday, July 1st 2014
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AMD "Tonga" GPU Arrives This August
In a bid to counter NVIDIA's bestselling GeForce GTX 760, AMD is preparing a new 28 nm GPU, codenamed "Tonga," as detailed in our older article on the chip. At the time of its writing, we had two theories on what "Tonga" could be, one held that it could be a counter to the GM107, and the other, that's is a step above "Curacao," in a bid to counter the GTX 760. We're now learning that AMD could launch the first graphics cards based on this chip, some time in August. The chip will replace the ailing "Tahiti Pro" silicon, from which is carved out the Radeon R9 280. While the R9 280 offers performance competitive to the GTX 760, it loses out big time on power consumption and heat. The cheaper R9 270X, on the other hand, offers lower performance, and similar power levels. "Tonga" could offer nearly as much performance, while featuring a new combination of components, that help AMD lower not just power draw, but also overall costs.
The 28 nm "Tonga" silicon is expected to feature 2,048 GCN2 stream processors, 128 TMUs, 32 ROPs, and a 256-bit wide GDDR5 memory interface. You'll notice that its memory interface is narrower than that of the R9 280, but performance is made up for with a higher stream processor count, and probably higher clock speeds, too. The card could come in memory capacities of 2 GB, with some manufacturers innovating 4 GB variants. There's no word on what the company could end up naming the first cards running this chip.
Source:
VR-Zone
The 28 nm "Tonga" silicon is expected to feature 2,048 GCN2 stream processors, 128 TMUs, 32 ROPs, and a 256-bit wide GDDR5 memory interface. You'll notice that its memory interface is narrower than that of the R9 280, but performance is made up for with a higher stream processor count, and probably higher clock speeds, too. The card could come in memory capacities of 2 GB, with some manufacturers innovating 4 GB variants. There's no word on what the company could end up naming the first cards running this chip.
25 Comments on AMD "Tonga" GPU Arrives This August
The loss of memory bandwidth (maybe not actual memory capacity as the 256bit bus will allow 4gb ala Hawaii) will deeply impact high resolution and heavy MSAA/SSAA performance. I expect this SKU to be extremely competitive with Tahiti at 1080p and under but it will bleed performance really fast at 1440p and beyond. That being said, if it comes equipped with 7Ghz or 7.5Ghz VRAM, the performance would be quite close to a stock 7970 of similar clockspeed. Something tells me they will equip this with 6Ghz modules or even 5Ghz ones if they recycle the Hawaii Memory controller design.
If it is priced at around the $250-$300 mark, its a real winner for the mainstream.
It's important to note that while Tahiti had it's merits for design (during it's heyday), a 384-bit/6ghz (1.6v) setup could essentially support 2048sp up to around 1350mhz. While that made sense for early silicon, now-a-days thing have evolved, with both GK100/Hawaii being higher up the foodchain and replacing Tahiti for the larger buffer/higher rez and also power envelope solutions. Clockspeeds on 28nm have also settled lower than on initial products as yield has increased...or at least that's how amd has been playing it.
Extrapolating, and assuming 2048sp is correct, I assume we get something around 1000-1050/7ghz. While on straight compute unit/bw efficiency it should have a clock similar to Hawaii, if you rather use a metric of what the average shader/fillrate usage is (ie they want to clock it pretending they are usually only using around 1880 units, essentially the practical difference between gk104 and Tahiti) it would be closer to 1050mhz or so.
I think the grand take-away will be exactly what this article puts forward: It will be a part between 760 and 770. Probably overclock to a similarish level to a stock 770. Hopefully it will be priced between the two, if not closer to the former, as well as being shorter and using under 225w (which using 2GB would imply...4GB may hamper clocks within that envelope)...essentially bringing Tahiti to Pitcairn's market (over time). IOW, exactly what others have postulated: this is (or will be, depending on your pov) the new standard for 1080p.
Anecdote and/or TLDR:
xbone is to Pitcairn (7870/270x) as PS4 is to....?
(Think about that for a minute, and do some 30->60fps and 720p->1080p conversions).
Make sense? ;)
Is there any truth that this is Pro version, and that there could be an XT as 2432sp part, but is holding it back (GloFlo having teething pain on yields)? It's certain this will be much more than the 760, while perhaps right on the back of the 770, and I'm inclined to think a MSRP of $240. Considering quite a number of 280's have been $200 here lately it holds some merit. Then latter an XT with 2432sp for $280-300, they could drop Tahiti altogether, and their margins would be excellent. Then if there is a 295 (full XTX Hawaii) with HBM could they bring it in at $600, and drop 290/290X to slot in at $350/500, while AMD has <$200 all tied up.
Giving the situation (TSCM 20nm miss-step) AMD is in a good place bringing GloFlo in and cultivating their production. If this is what's happening AMD might see the chance to perhaps not take a huge bite of market share, but provide a true alaround 1080p card for under $250, and have them see really good margins on those sales. I agree with everything but 225W! The 7950/280's are 200W parts, a 760 is 170W I couldn't imagine 225W making the grade. I would hope that efficiency is a big part of the mix and if it isn’t in the new architecture (GCN2.0 or whatever) it's no-starter. Especially if from GloFlo as that would be a terrible reflection on them, it would be hard for GloFlo to come out of the gate making that for AMD if that is what Tonga delivers.
I think on this they’ll want to be at minimum closer to 170W. We won’t see GK107 type efficiency, but for a true 1080p full-Enthusiast quality experience I think in perf/w it will be fine if they can emulate what OC’d GTX750Ti have provided.
In order to keep the cards efficient (ie: performing without shedding too much heat), AMD can do a few things
1) A 256-bit memory bus (actually 2x128-bit) = 2GB of GDDR5 RAM. That's the same as the GTX 760 and I don't think it'll make much of a difference in terms of a lower framebuffer than the R9 280. AMD can stick in 1.5GHz GDDR5 instead of 1.4GHz, making up for the loss of bandwidth with increased throughput. This also makes the card cheaper.
2) Reduce GPU overhead = this a bit more arbitrary and involves a lot of software optimization, not only hardware optimization... this will keep both idle and active power consumption lower than the current Tahiti Pro.
3) Better control over GPU power states = also through hardware and software optimization, AMD will need to really get this right if they want to cut idle power, which is usually higher than Nvidia's. Power/Clocking up/down efficiently is critical.
4) Reduce Double Precision FP performance = The Tahiti XT GPU implementation has a massive advantage over its siblings in Double Precision FP performance, and even a greater one over the GTX 760. If AMD can trade-off Double Precision FP performance for power savings... :)
All in all, and staying with the 28nm node, there isn't much more that AMD can do except adjust to the competition's own products in the same shelf.
Some sites are calling Tonga a replacement for Tahiti, but if we're talking about slimming down the card, it's not a replacement, but a new SKU... with a different price point. Any ideas?
www.techpowerup.com/gpudb/2405/radeon-r9-280.html
I think AMD is focused on only the superlative in Gaming Mainstream 1080p. They can knock down a good amount of the DP for more SP / efficiency, all in a smaller package. I'd think a 25% drop in TDP might be realized, they have to just be as proficient vying GK104’s not even looking forward to if Maxwell scales. A very cost effective card for the bulk of gaming.
Still, they need to pull off a cheap power-saving stunt without sacrificing too much performance to trump the GTX 760.
I used the example of using higher-rated GDDR5 even with the bandwidth reduction as it would match what Nvidia has on the GTX 760 ... and all things equal, AMD needs to work on a whole bunch of things to get it down to the GTX 760 power envelope.