Well you do realized that achieving actual GB speed is not possible. The GB speed is a physical connection speed between devices and getting a thru put at that speed is not possible at this time. Same thing with 5Ghz N mode WiFi 300Mps. Max speeds I see on my Mac Laptop is 10Mb for file xfers. These are just connection or link speeds, not file xfer speeds. However realistically you should be seeing upwards of 20-60Mbs at least.
However there are some factors that can contribute to xfer speeds:
OS, PC HW, HDD speeds, loaded 3rd party sw and such.
I know is sounds crazy that technically you should be throwing 900Mb speeds over a Gb line. Wouldn't that be nice. One day I guess.