The extra free space seen by Explorer at one point (700GB vs 500GB) is something I can't explain from your description. Since you have a 3TB drive, is that drive formatted with a GPT partition table? Is all your data on the HDD intact?
If you install the Intel Rapid Storage driver package for Windows, part of the package is the IRST UI that allows you to create and manage RAID volumes, and create a SSD caching system. The latter is called Intel Smart Response Technology, or accelerating the storage system. The IRST UI has an extensive Help support option, that opens a separate window with information about creating RAID arrays and creating a SSD/HDD caching system, and its requirements.