One of my hard drives can't tell which one spins and whirrs and clicks. But it still works whichever one it is. I can still store files copy files from it etc. What could be the problem? I'm guessing it's my new 1 TB hdd.
What model drive? WD's Green drives will park it's heads ALOT to save power, but's fairly quiet when it does that and it sounds more like a scrape than a click. If it sounds more like a loud click, then it could be your drive going bad.
Unplug other drives isolating only one on at a given time and let it run to figure out which it is... then BACKUP and RMA since drives shouldn't click or whirl except on a cold boot (some hdds make clicking sounds as the heads move). Just idle, no way.