Run ATTO and AS SSD benchmarks and post your results.

With AS SSD, click on Sprache and select English to change the language.

This should show if there is a problem.

Using the Intel usb 3.0 ports should give you the best read/write performance.
Your mobo user manual will show you which usb 3.0 ports are the Intel ports.

I was copying several large folders today from my 4K-aligned hard drive to the external drive which has 4K-aligned partitions and my average throughput was about 65 - 75 MB/s (not mbps).
With a lot of very small files, the throughput was 1 - 10 MB/s.
When I'm copying large files, 50 - 100MB, the throughput to my external averages 100+ MB/s.
When you use win7's Disk Management to format a new drive, windows will automatically align your partition(s) on a 4K boundary.

The attached screen-shot was taken when my external hard drive was new.
See my signature for the details of my P35-DS3L / dual core system.
I'm using a HighPoint 1022A usb 3.0 controller add-in card.

My system is half-fast compared to your system.

GA-Z77X-UD5H usb3 performance degrade ,plz help-toshiba-canvio-desk-3tb-usb-3-0-black-desktop-external-hard-drive-hdwc130xk3j1-benchmark-info-jpg