I’d be wary of the Taichi. I tried the 3700X in my Asrock X370 Killer AC / SLI and it refused to operate normally. Voltage on vcore was out of control and I could never get my memory above 2133. Works fine on other (non-Asrock) boards. Had similar issues on the Asrock Fatality B350 ITX (though even more pronounced).
Granted, the Taichi has a better VRM as I recall and most of my issues were likely more BIOS related but it may be something to bear in mind.
That being said, the 1700 I’ve had in that Killer AC for the last two years has been pretty solid, though I think my memory controller has degraded a bit from being overclocked to 4 GHz a fair bit of its life.
I’ve got an X470 taichi (admittedly with 2700x and not 3700X) and have no complaints, other than the UEFI being a bit clunky.
My non-b-die dual-rank 2x16GB memory is running at DDR4-2866 CL15. If you can’t get above 2133 i’d say either your board, memory or CPU is a bit busted; you should be able to get better than that.
Sorry, I wasn’t particularly clear - the memory only exhibited that behavior on my ASrock boards paired with the 3700X. Slapped the 1700 back in and it was back to normal, which for that kit (Corsair 2x8GB non-b-die) is 2800 CL14.
Pretty sure it is most likely an issues with ASrock’s implementation of the last pre-release Agesa…
Either way, I’d assume it will get worked out eventually by a new bios.