I'm getting same speed from USB 2.0, USB 3.0 and USB 3.1 from my Transcend's StoreJet 25M3 portable hard drive
PC Spec:
Intel i7 6700k
gigabyte z170x gaming 3
SSD ADATA SU800NS38
HDD WDC WD10EZRX-00A3KB0
RAM g.skill Ripjaws v ddr4 12GB(8+3)
graphics card Nvidia GTX 960 4GB
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PC Spec:
Intel i7 6700k
gigabyte z170x gaming 3
SSD ADATA SU800NS38
HDD WDC WD10EZRX-00A3KB0
RAM g.skill Ripjaws v ddr4 12GB(8+3)
graphics card Nvidia GTX 960 4GB