If you're looking for a way of calculating an estimate temperature for your setup, you're best off just looking at forums for someone who has the same build and has released their temperature readings at load.
The problem with what you're asking is that your CPU temperature is TOTALLY dependent on YOUR environment; the ambient room temperature, the cooling system of the case, other component heat generation, how you use your computer, how your air flow is directed through the case etc etc. The wattage of a cooler doesn't really dictate how efficient the cooler is. You're best off finding a particular model and set up, and search online for others with the same setup.
If you're asking for software to actually tell you your current CPU...