Processor Core temperature meter app, anyone?

Im looking for a (free) app for OSX that will measure core temperature for the processor cores on my Mac Pro.

I have tried some apps but i don't get the exact core temperatures.

Since i just did a processor swap i want to make sure the cooling paste is applied correctly, and that all cores get even cooling.

Does anyone have a good app for this? I tried google with no good result.

Thanks!