WD CB HDD Noise (iMac)

I have a circa 2008 24" iMac 2.4Ghz and recently had my HDD professionally upgraded  to a SATA 1TB WD Caviar Black (CB). My problem is that after about 2 hrs and 15 min, the drive begins to “humm” - no clicking noise, no loss (so far)  or change in performance, but the humming sound is pronounced and annoying.  In reading other posts, I understand that the CB is a high performance drive and may run a little hot, but I’m concerned with the constant noise.  By listening to the back of the iMac, it is not the fans (they are not that noisy) - it does sound the like the drive.  

Any ideas or suggestions would be appreciated.



The type of noise and the volume of the noise can change depending on the current function that the drive is involved in. It is important to recognize which noises indicate trouble and which are simply normal drive sounds. Please see the WD link below: