short answer: idle speed doesn't matter, its controlled by manufacturer already. Look at heat when system is taxed, ie...playing a game. after the fan calculations and such are dont you should be no more than 75 C.

Long version:
It all depends on what is attached to the system itself. The heat generated is less significant since its already been tested for and controlled by the manufacturer. So it depends more on what you got in the hood. (water cooled, # of fans, fan speed, are you overclocking it). SpeedFan is a great program to check on all that.

With that in mind idle speeds dont really matter because they are controlled by manufacturer... youll be fine almost no matter what. What is the speed when you are for instance doing something taxing on the system that's when you really need to watch temp. here is an example I have a similar processor,Amd Athlon II X4 940, when I max this sucker out im at about 70 Celsius... been running at that temp for a about a year now... that should give you some indication.

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