I was having issues with a Seagate momentus xt 750 hybrid drive. Using HD Tach the tranfer rate was all over the place average only 77 Meg per second. A second drive same exact drive, both were bought at the same time did 95 megs average. This was using both on USB 3.0 same enclosure. I quick formatted the slower drive no change. Then full formatted it and now it speed averages 100 meg per second. Both drives pass smart. Now it concerns me that quick format is not the way to go. Both drives had the same reallocated sector count 100. I know that full format remaps bad sectors. I am wondering if I need to start full formatting all my mechanical drives? I use them for games and data my os is always on SSD.