It is possible the HDD's are about to go. I've tried putting FFXIV on both drives, same issue on both. The one FFXIV is on now (the Velociraptor) should only be maybe 2 years old if that, so it's life should be fine. Reinstalling Windows is also a possibility, I did that around 1-2 years ago, so it should in theory be fine still too, but it might be something to try (only avoiding doing so due to nasty data caps my ISP has).