So I tested the USB 3.1 gen 2 ports with a 2 drive raid enclosure (ASM1352R, 2x2TB EVO SSD raid 0). MB has three USB 3.1 gen 2 ports, that are divided to a two separated controllers: ASMedia (ASM????) = type C + A and AMD chipset (X399) controls 1 on the motherboard PCB -> type C.
Since the ASMedia(ASM????) is split to 2 ports (used 1), I suspect it is causing the ports to be ~10% slower on all test with crystaldiskmark when compared to the AMD one, also the X399 chipset has the advantage of direct connection to the CPU.
1950X 3700Mhz, NUMA. SMT off. 64GB/4 3200Mhz CL14 CR2
Single thread/queue(1) sequential write ~562MB/s, single drive enclosure(ASM1351) ~375MB. "file copy"
Two thread/queue(1) sequential write seems to cap something at ~875MB/s, got about the same results with high queue number tests.
Sequential read speeds hover around the 700MB/s ± 20MB/s on the tests.
Test results seems to vary somewhat, also managed to get the enclosure to get stuck in super slow speed somehow.
Need to test the SSD raid speeds some day on the PCIe add on card that I use for spinning disk raid, and on the MB sata slots (all in use).
Now waiting for USB 3.1 gen 2 to PCIe NVME enclosures to become more common/available (JMicron JMS583, ASMedia ASM2363), and large size NVMe to be a bit more affordable.
+Ran into some serious PC slowdown issues with large thread count test while testing on the X399 USB port, while the ASMedia ports worked normally, waiting for reply from AMD support, this also happened with the single drive enclosure.