Does the low grinding noise stop when the hard disk is in use (copying or moving some files for example, or doing a time-consuming export or save)? It might be that what you are hearing is the hard drive performing regular surface tests (extended SMART self-tests)... these only run while the hard drive is idle, so the noise will go away in case of any actual hard drive activity. Sadly, the low grinding-seeking noise usually comes back the next time your hard drive is idle for a while, since the surface checks will pick up where they left off until a full cycle is complete.
beh sarebbe in linea con tutte le altre schede, no? È sempre così.