I switched usb 3.0 ports and got the same results for both, but noticed something else. My external drive is divided into 2 partitions (2tb and 850gb). When copying to the big partition it goes at a steady usb 2 rate, but copying to the smaller one starts off real fast (like 200 mb/s) but quickly drops to about 30 and seems to freeze after a few seconds, but the file being transferred changes real slowly, like it's really transferring just at slower speeds. I even tried the usb 3.0 ports directly into the motherboard in the back. Same result. I also took a usb 2 cable and connected it, same exact speeds. So I dunno if my usb 3 cable is bad, my external drive, or my motherboard.