On initial launch, the motherboards were *super* flaky. Beta status at best...
SMT (Hyper Threading in AMD speak) would mysteriously disappear.
Change an unrelated BIOS setting (disable onboard Audio) and the motherboard wouldn't boot with RAM at 2667MHz.
Several months down the line, motherboards have solidified a bit.
However, there's still some flaky behavior.
We had one scenario (recently testing X370 motherboards with RAM at 3200MHz) where the motherboard would let you into the BIOS... and immediately lock up. The behavior continued even after clearing CMOS.
Had to pull the RAM to get motherboard back to normal function.
At this point, there's no way I'd build a Ryzen based DAW for clients.
Intel X99 motherboards are mature and rock-solid
ie: You can install DDR4/3200 in just about any major X99 motherboard... and it'll work just fine.
Ironically, there's not a major performance benefit for using higher speed RAM.
These things said, we do have an 1800x based DAW here in the studio.
Overall, it's running pretty well.
We've got 32GB RAM running at 3200MHz.
Still waiting on further BIOS updates... to improve RAM compatibility and eliminate issues when changing parameters.
With fast RAM, the 1800x does best the i7-6850k running DAW Bench (low-latency audio stress-test).
Healthy competition is good for everyone...
Intel hasn't had serious competition for at least a decade.
Ryzen has the potential to be serious competition.
AMD's next generation "Threadripper" CPUs are even more enticing.
Up to 16-cores (32 Threads) and 64 PCIe lanes...