My Intel Pentium D is at 85 degrees Celcius

Hello, I have noticed that my Intel Pentium D 945 3.4GHz Processor is running at a relatively high temperature. I am using a Stock fan and I recently (around 5-6 months) changed the thermal paste of the Processor. My Mother's computer is running with an Intel Celeron 2.66GHz procssor and the constant temperature is 46 ºC /114.8 ºF . Actually my cpu temperature is 82ºC / 179.6 ºF. I installed the "Dual Core" program whose purpose is to check and warn the user about any malfunction of the CPU. The program rang an alarm and warned me that the CPU temperature is too high and it shut down the system. Please note that I do not have any problem with the processor, it doesn't restart without warning. The only thing I noticed is the performance. Long ago I was able to play PES 2011 on max settings without any lag now I play for 5 minutes and after that the game lags horribly. I am sure that it isn't the fault of the Graphics Card as I tested it on my friend's computer.
However , here are my technical specifications:





Thank you for your help

-Michael