@Pinto2

You are getting a great transfer rate under USB2. 21MB/s is really great performance and will support the NEC at 12X with no problems, but you need a little more to support 16X.

ON YOUR PROBLEM !!!

May I suggest you try the external setup on another machine to determine if you setup has a problem. I have no knowledge on your VIA Firewire chipset on your motherboard...