The Lynx Point PCH used in your WY NUC has a single xHCI controller that supports 4 USB 3.0 ports and data transfers of up to 5Gb/s (640MB/s) per port. This is, however, limited by the overall capabilities of the DMI bus that connects the PCH to the CPU. Broadwell processors support DMI 2.0, which has a maximum throughput of 8Gb/s (1GB/s). Is 650MB/s possible across a set of these USB 3.0 ports? Certainly, but remember that the DMI bus is also used for SATA and many other interfaces...