CrystalDiskInfo is a hard drive health monitoring tool that displays drive information, disk temperature and monitors S.M.A.R.T attributes. CrystalDiskInfo can be configured to trigger an alert (i.e. write to the event log, send an e-mail or make a sound) when a certain threshold is reached, so it can be left to actively monitor the HDD and notify you automatically.
The bar at the top displays all active hard drives. Clicking on each one will display the information for that drive. The Health Status and Temperature icons change colour depending on their value. - (gfi.com)