USB 3.0 on Linux ( AMD processors )

You'll find at times that your USB 3 device is running on USB 2 speeds. This  can be addressed by passing a  kernel parameter in grub. "amd_iommu=on" 

The input–output memory management unit (IOMMU) is a memory management unit (MMU) that connects a direct-memory-access–capable (DMA-capable) I/O bus to the main memory.

To make the changes permanent, add the parameter to /etc/default/grub 

GRUB_CMDLINE_LINUX_DEFAULT="amd_iommu=on"

and run "sudo update-grub"


Remember that  the effective transfer rate will be dependent on internal disks and other possible bottlenecks .