Core Temp is a very compact, small sized and free utility that works to monitor the temperature of your CPU.
The biggest advantage of Core Temp is that it can show you the individual temperature of each processor in your system. You can see how the temperature varies when you load your CPU, in real time.
Core Temp also has a log function, that collects everything done and the data produced, so you can study it more easily or transfer it, for example, to a calculation sheet.