1Gbit/s is the bandwidth
of your internet service, not the download speed.
The download speed is the bandwidth divided by 8 (since there are 8 bits to a byte).
The actual Download Speed
is therefore 1,000 megabits divided by 8 = 125 Megabytes/sec
, and remember that's just a theoretical maximum under ideal conditions. It's well below the write speed of either of your hard drives.
See this: http://www.tomshardware.com/reviews/gigabit-ethernet-bandwidth,2321-3.html