Did you try this ?
Originally Posted by Hefemeister
get some good thermal paste. I recommended tx-2.
If I remember my AMD correctly there is a lever bar that you pull out and up to remove the heatsink.
clean the old thermal paste off of the cpu and heatsink. coffee filter and rubbing alcohol works good.
apply a single rice grain amount of the thermal paste on the center of the cpu. replace the heatsink in the same fasion as you took it off.
You can also search around for guides on specific parts of the task.
That proses isn't to clean dust off your heatsink, it's purpose is to replace the thermal paste currently on you cpu with new high quality thermal paste (Tuniq TX-2) which will lower your temps.