SpeedFan is a program that monitors voltages, fan speeds and temperatures in computers with hardware monitor chips. SpeedFan can even access S.M.A.R.T. info and show hard disk temperatures. SpeedFan supports SCSI disks too.
Temp Monitor app is an unobtrusive tool which will alert you when your Mac overheats, and the perfect utility to help you log all instances when the processor goes beyond a temperature which might be dangerous for both your Mac and yourself, if you’re using a MacBook or MacBook Pro.