Well, it's either a fan, which is most likely, or its the bearing starting to go in the drive, in which case it should have shown up as a spinup issue under seatools. if the drive is on the smaller side and you don't have a backup in place, i'd replace it anyways with a larger one since drives are cheap. It's probably dust in the video card fan though. the reason that grinding would go away upon entering ffxiv is that once the fan kicks into higher revolution mode the bearing drag you are hearing as grinding goes away because the fan itself is spinning too fast. It's like the old card in the bicycle spokes trick.