AMD GCN Update: Iceland, Tonga and Hawaii XTX

Published: Jul 15th 2014, 09:33 GMT

AMD will soon update Graphics Core Next architecture with three processors: Iceland, Tonga and Hawaii XTX.

None of those GPUs are secret to you, we’ve already covered all of them in our previous posts. However for the sake of clarity, we are going to remind you what is known to this day.


When we first heard about Iceland, we thought it was a new Hawaii successor. However, Iceland is something completely different, a mid-class processor. Most importantly Iceland is mobile GPU, however it will launch as desktop card in later date. Iceland will finally send Cape Verde to retirement. For such reason, Iceland might be the actual Maxwell GM107 competitor.


Tonga is basically a Tahiti core with 256b memory bus interface. Tonga is going to be launched as new SKU, not as a Tahiti replacement. Both solutions will coexist on the market until AMD introduces its Radeon 300 series.

Hawaii XTX

New Hawaii revision, which we’ve told you about two weeks ago, will be the fastest AMD’s SKU for this year. Some of you asked why did we remove the post about XTX. Well, it was only because we wrongly assumed it will be a 3072 core GPU, which is not true. Hawaii XTX is basically the same thing as XT2 or XTL revision to Tahiti. Hawaii XTX is simply higher-clocked Hawaii XT, nothing more and nothing else. From what I’ve gathered so far, XTX will be launched with Radeon R9 295X.

Only at VC: GCN update features

Now, we are going to tell you about new architectural improvements coming to GCN. Unfortunately we were unable to confirm whether Hawaii XTX will support them too.

UAV Ordering (Unordered Access View Ordering)

UAVs cannot guarantee that each frame will access pixels in the same order. In order to avoid artifacts, some sorting is required. AMD’s UAV Ordering is basically a copy of Intel’s PixelSync. It’s a special algorithm to solve three problems: order-independent transparency, complex scenes anti-aliasing (for example hair or fences) and shadows from transparent effects.

This technology will drastically change the complexity of the scene in newest games.

A good example of such algorithm being used is shown below.

GRID2 PixelSync

Fast Conservative Rasterization

While UAV ordering is just a software algorithm, Fast Conservative Rasterization will be a hardware upgrade. Conservative Rasterization is nothing new. However current implementation is slow, and everyone who ever tried TressFX knows that very well. Disabling TressFX makes hair strands thicker. Since this technology is also using order-independent transparency, new features will considerably speedup the process, thus allowing the scene to be rendered faster and more complex.

AMD developing 28nm GPU, core of Radeon R9 390X.

Synapse Design 500mm AMD GPU

Synapse Design is a company responsible for AMD’s chip floor designs. Synapse recently announced new GPU tapeouts, including two 28HPM silicons (this was discovered at Anandtech forums).

The first one is relatively large chip, 500 The 28HPM is as powerful as 20nm SoC architecture, so this might be the new Radeon flagship GPU. This processor would run at 1GHz frequency, and according to the source, it will not feature HBM (High-Bandwidth-Memory).

The second GPU is silicon. There is a good chance that this particular chip is actually Tonga. We did confirm that Tonga is almost as big as Tahiti, sound reasonable.


This is all for now. We are currently expecting more information about Tonga, mass production starts in two weeks. We should see more leaks somewhere in August, so stay tunned.


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