CoreTemp is a freeware utility that lets you monitor your CPU Temperature via System Tray. In its dialog window it provides information about your CPU i.e. its model, clock speed, its temperature and percentage load on CPU. It also gives a warning on overheating of CPU.
If your CPU has multiple cores as is the case with dual core or quad core processors, it’ll display temperature for each core as a separate icon in system tray. By default it updates CPU temperature reading every 1000 ms, and also logs temperature to a log file every 1000 ms.
You can adjust the time span of refreshing the temperature reading and that of logging temperature via Settings Panel under Options Menu. You can set it to start in minimized mode and also make it run with windows startup via Settings panel.
You can control how the tray icon is displayed via Options > System Tray Setup. CoreTemp does not require installation, just download and run.
This utility is especially useful for users having powerful machines and overclockers.