You are ignoring the fact that even those 8 CUs are memory starved. If Vega is to bring another memory compression update, even 8 Vega CUs will be enough of improvement over 8 GCN1.2 CUs to warrant calling it a significant upgrade. You do have a point, though, 11 CU is not a sensible number.
All rumors come from somewhere. If my memory serves me right, Skylake was hyped by B&C as a big update too.
That is exactly why 16 CU design will have HBM2. To completely lift off the problem of bandwidth.
However, let me give you a little perspective. Depending on the application in gaming scenario, and how well it is "modern", in technical terms, the performance gains from Vega architecture will vary.
Lets assume simple technical stuff. 1024 GCN core chips from Polaris and Vega architecture. RX 460 1024 core, and Raven Ridge GPU.
Raven Ridge APU in Overwatch will be 25% faster, clock for clock from Polaris, just because of the improvement in throughput of the architecture, that is not needed implementing to the game.
Raven Ridge APU in Doom, with game updated to take all of the hardware features, will be up to 75% faster clock for clock, compared to Polaris architecture in similar scenario. But it will require redesigning a bit the pipeline and updating the game for the Vega Hardware(Primitive Shader pipeline, etc...).
I will not even mention all of the compute improvements, because how I understand that is, AMD changed a lot of how the GPU handles registers, to achieve higher clocks that Polaris. Vega appears to truly be future proof architecture, and really will need HBM2 to shine, even on such small chip technically like 1024 GCN core design.
And 16 CU's + HBM2 will appear in massive amount of markets IMO. Embedded, Machine Learning, Gaming, HTPC, normal, cheap, power efficient computers, everywhere. If you ever thought about one solution where you could fit everywhere - it is APU. And this design will be a great start for the foundation of creating
mindshare. If AMD wants HSA to start truly get traction, this is the only way.
Dislaimer. Those are only my thoughts on what will happen, and some rumors from professional space, but nothing too specific to share.
- Write cost for Polaris 11 upgrade here:
- Write cost for new AM4 system here:
- Compare costs
Also, here's how this line of reasoning looks from another standpoint: why would anyone buy an AM4 APU if they could get a faster RX 460 instead?
You have forgotten about the improvements in performance of 1024 GCN core chip. It can cannibalize not only RX 460, which is not 1024 GCN core design in mainstream market, for very good reason, but also 1792 GCN core RX 470D, which is not in the market, for very good reason.
If you get this level of performance for lets say 300-350$, and you get more efficient, and much simpler design, why would you buy any of those cards? Why would you buy a CPU, if one chip can do everything, for the masses?
You get the perspective right now?