You are forgetting about new gpus. CPU mining will never be as good as GPU mining due to CPU to GPU cost comparison. If you invest same amount of money into CPU and GPU mining you would get ROI much faster on GPU rigs.
There will always be new CPU's and GPU's
CPU mining rigs are not so convenient but I figure that GPU shack setup exist for a reason. Looking at this page there are CPU's that can mine a decant amount on XMR and there may be future coins that do well for CPU's. CPU's also have the chance to really farm up some early alts and sell on the pump http://monerobechmarks.byethost5.com/
ill add the following (it is afaik not confirmed, we will need to see):
It will reduce the compute power of AVX2 code which will affect some algos, mostly Lyra2 based algos, algos that use
cubehash (x11 family) and Hodl, essentially any algo that reports AVX2 capability. However, if an algo is I/O bound a small
loss in compute power may not affect the hashrate significantly. I'd think twice before buying one for mining.
Edit: I expect the performance to be equal to AVX, maybe a little better.
Edit: I don't know what will happen to AVX2 intrinsic or assembly code. If Ryzen doesn't recongize AVX2 instructions it may
have to rely on the compiler not to generate them. That won't work for hardcoded AVX2. If, on the other hand, Ryzen
internally converts them to their AVX equivalent that won't be a problem.
im not sure about the server cpus, they will likely have the avx 256 included (?), would be interesting to see their performance if so
small question to joblo (or anyone competent in that field, im not 
)
i just read the following about upcoming ryzen arch:
if this turns out to be true, does it have an impact on mining speeds? i suppose yes
cheers
)i just read the following about upcoming ryzen arch:
Quote
AMD left out 256bit AVX to save space and power to allow for higher clocks, but it can still decode avx, but it uses 2x128 bit, so it takes 2 cycles for 1 avx instruction.
if this turns out to be true, does it have an impact on mining speeds? i suppose yes
cheers
It will reduce the compute power of AVX2 code which will affect some algos, mostly Lyra2 based algos, algos that use
cubehash (x11 family) and Hodl, essentially any algo that reports AVX2 capability. However, if an algo is I/O bound a small
loss in compute power may not affect the hashrate significantly. I'd think twice before buying one for mining.
Edit: I expect the performance to be equal to AVX, maybe a little better.
Edit: I don't know what will happen to AVX2 intrinsic or assembly code. If Ryzen doesn't recongize AVX2 instructions it may
have to rely on the compiler not to generate them. That won't work for hardcoded AVX2. If, on the other hand, Ryzen
internally converts them to their AVX equivalent that won't be a problem.
im not sure about the server cpus, they will likely have the avx 256 included (?), would be interesting to see their performance if so
There just had to be something missing. I'll have to look into what avx256 is needed for before making a Ryzn rig. Probably not happening this year anyway for me.
.
