So this noise is not the usual HDD click click click noise that you'd normally hear from a HDD when it's doing something? HDD's always make a noise. Especially bigger, faster ones. Whenever you access the HDD by opening a folder, file, application, whatever, i'd expect to hear lot's of fast clicking noises. If it's much louder, like a DVD drive, then something's probably wrong. It's also worth ejecting any DVD/CDs and trying again, as often (at least with windows) when you launch a file explorer, it polls the DVD drive too and a dirty DVD can make it pause and think.