What are you seeing?
In an Intel® Series Chipset platform with Windows 8* installed, some USB 3.0 devices are only working at USB 2.0 speeds.
Why are you seeing it?
The most common issue: The port might be routed to the ECHI controller instead of the xHCI controller. Check in Device Manager > Universal Serial Bus controllers.
Another possible issue: Some 3.0 USB devices are not compatible with the Windows 8* USB 3.0 driver.
Upgrade the BIOS to latest version. Get the latest version BIOS from your OEM.
How to fix it through enabling the xHCI mode setting
If the BIOS upgrade does not fix the issue, set the xHCI mode setting in BIOS to enable.
Check with the USB 3.0 device vendor to see if you can upgrade the device firmware.