Before recently deciding to upgrade my early 2009 Mac Mini with an SSD, I noticed the original HD was only negotiating data transfer speed at 1.5Gbps even though this Mini is capable of 3Gbps. How could the original equipment be running at SATA I level on a SATA II machine? Can the HD deteriorate over the years? Or latest El Capitan update? Or maybe it always was that way (I had never checked before).