Like flank said, it should automatically be adjusting its clock speed as needed. Enable "intel speed step" like he said if it wasn't enabled by default (it should already have been if you never touched anything in the BIOS).
Also, assuming everything is working correctly, it will downclock all the way to 1.6ghz by default if you are just webbrowsing or typing word documents. At least that's what it does for me. You can also check your cpu speed by using the free program "cpu-z". Just do a quick google search for it.
i know it downclock it self what i mean is to limit it's clock speed to 3ghz if it is safe