and people prove the point downloading new shit because they hope for the best:)))
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There are architectural changes which affect how code is scheduled:
Single cycle instruction issue:
GCN issued one instruction per wave once every 4 cycles.
RDNA issues instructions every cycle.
Wave32:
GCN used a wavefront size of 64 threads (work items).
RDNA supports both wavefront sizes of 32 and 64 threads.
Workgroup Processors:
GCN grouped the shader hardware into "compute units" (CUs) which contained scalar ALUs and vector ALUs, LDS and memory access. One CU contains 4 SIMD16s which share one path to memory.
RDNA introduced the "workgroup processor" ("WGP"). The WGP replaces the compute unit as the basic unit of shader computation hardware/computing. One WGP encompasses 2 CUs. This allows significantly more compute power and memory bandwidth to be directed at a single workgroup. In RDNA 1 CU is one half of a WGP.
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So as u can see most of old GCN gpu works in wavefronts of 64 threads in 4 cycles, and new RDNA is doing instruction every cycle. So what i my guess is that that on driver 19.9.2 u could force driver to give 5700xt 64 threads to deal with and then cards were showing hashrates up to 58mh even more but it was also giving incorrect shares so effective hashrate was acaually lower than it was showing on miner console. Now once again my guess is that via wavefront of 64 on Navi u were just giving too much instructions to gpu that gpu just could not handle, since on GCN they were done in 4 cycles and here they need to be done in one cycle. So i suppose later on there will be some new kernels optimized for Navi architecture that will be able to get that hashrate without any incorrect share. Take this with grain of salt, i am far from expert on this field, this is just my understand of it.
Interesting, I lost you at the end, keep thinking how is it known that "gpu cant handle", because if you see bad shares you can actually understand it's not working, so your rate is shit. but now if its about Navi then I don't have any ... yet (is it the 7nm one? like in two flavors 5700 and 5700xl or something?)