Speed external USB drive SH14

[alexa1970]

I buyed external HDD SH14 1TB USB3.0
On box Transfer speed 5Gb/s
In internet on them site:
Read 109.6MB/s
Write 107.2MB/s
Really Transfer Speed 21GB 6min and 9s ~58.276MB/s
It's ~50% from Speed Adata in internet
I work under Linux Mint13 Maya
CPU i5 2300
motherboard GA-Z68X-UD3H-B3
memory 16GB 1333