I've also had problems with a hard drive not being detected intermittently, with no other issues (ticking, errors, etc...). Power is probably the #1 culprit in these cases. I put the drive on a different rail, and it worked fine for a while at least. Due to some other issues, I eventually moved the drive to a different system (with a lower watt power supply), and it works fine to this day.
So I would first try switching around which rail it's on (especially if it is sharing a cable with a power hungry graphics card). Double check the data cable of course. Consider buying a quality power supply. And either way, make sure your data is backed up if it really is the drive.