i very well understand what you are saying, but still i havn't got my answer yet. If i plug usb 2.0 in usb 2.0 port why can't i get 60MB/sec data transfer speed which it intended to provide (480mb/sec) same goes for USB 3.0. I know , if i put usb 2.0 in usb 3.0 port we wont get usb 3.0 speed "magically", but what happened when i plug usb 3.0 in USB 3.0 port but still we dont get the intended speed (600MB/sec or 5Gb/sec)? i really appreciate if someone give me the complete explained answer. Thanks