Sounds like you might not have gotten the thermal paste done properly.
When you are ready to install a CPU cooler, plug the fan into the motherboard first. set it aside for now. Put down a drop of thermal paste about the size of a grain of rice, right on the middle of the CPU lid. Then best you can, lower the CPU cooler straight down onto the CPU Lid, insert all four screws loosely, and then tighten them one turn at a time in the following pattern:
1 - - - 3
- - - - -
- - - - -
4 - - - 2
Continue cycling through the screws in that order until all 4 are nice and tight. Try not to move the CPU cooler anymore than is necessary. Let the CPU cooler spread the thermal paste for you. When the cooler block is tight, attach the fan to the block.
When it is done properly, and the system is at idle, you should see temps below 40c. I see 33c on my system at idle. I also never let my CPU go over 70c. If you see your cpu climbing above that, you either need faster fan speeds on the CPU cooler, a second fan on the CPU cooler, and/or you need to redo the thermal paste.