HDD interface speed

Solution
The SATA standard is "Backwards Compatible." That means you can connect a SATA3 device into a SATA2 controller and everything will work, just at the SATA2 speed.
Yes, your HDD will work the same and have the same Read/Write speeds whether it is connected to a SATA 3Gb/s port or a SATA 6Gb/s port.

HDDs can be SATA 6Gb/s "compatible", but they are not 6Gb/s "capable". No HDD can spin fast enough to achieve 6Gb/s speeds.