Even in a perfect world you would be hard pressed to reach the max bandwidth. You have to have everything off and the computer has to be at no load. Its just like a Cable modem even though they boast speeds of 15mbs your sharing your connection with several other people. If they are all online you will never achive 15mb/s. Your computer has allot to process while the port is capable of 480mbs your computer may not be..
""As far as we know, effective rate reaches at 40MBps or 320Mbps for bulk transfer on a USB 2.0 hard drive with no one else is sharing the bus. Flash Drives
seem to be catching up too with the some hitting 30MB/s milestone. For all we know, USB interface could become become the bottleneck for flash drives as early as 2008. Additional notes from Alex Esquenet - our engineer friend based in Belgium: "A fast usb host can achieve 40 MBytes/sec. The theorical 60 MB/sec cannot be achieved, because of the margin taken between the sof's (125 us), so if a packet cannot take place before the sof, the packet will be rescheduled after the next sof. On top of that, all the USB transactions are handled by software on the PC. For instance, a USB host on a PCI bus will send or receive the data via the PCI bus; the stack will prepare the next data in memory and receive interrupt from the host."