Good info. Thanks for sharing. My Fury x's are only a few Mh faster than my 390's. I believe all GPU development was done on a 7850 so that makes sense. No way 4096 cores shouldn't be a good 30-40 percent faster. One nice side benefit of HBM is you can set it to 300Mhz and still achieve almost the same speeds as 545. Saves some energy too.
It's a shame no one has been able to optimize the development over time for faster GPUs. As difficulty kept increasing with BTC, we upgraded from HD4800->5800/6900->7900, etc. but if no further optimizations happen, even if we get 5000-6000 shader Vega cards, it might hardly make an impact unless something changes in AMD's GCN 4.0 architecture.
As a point of reference for BTC:
VLIW-4 6970
1536 stream processors @ 996mhz = 3.056 Tflops = 422 Mhash/sec
GCN 1.0 7870
1280 stream processors @ 1165mhz = 2.982 Tflops = 423 Mhash/sec
https://en.bitcoin.it/wiki/Non-specialized_hardware_comparison
GCN became far more efficient for games but it hardly made an improvement for BTC mining. I fear a similar result for GCN 4.0 since I presume modern optimizations will be made towards graphics workloads. I mean some of these are not even related to hashing.
Geometry Processor
Multi-media cores
Display engine
and we both noted that memory speeds don't have much influence.
That leaves Command processor, L2 cache and GCN 4.0 as any remaining parts that could have a significant impact.
But then the increased IPC could mean AMD would limit Polaris 10 to just 2304-2560 stream processors, which wouldn't translate into a linear increase in hashing uplift as opposed to if they straight up replaced 2560 GCN 1.1 R9 390 cores with a new 4096 GCN 4.0 core part.
I am not too optimistic.