I'd replace the whole Fan / Heat sink with a passive one - cheaper and easier - held up to my overclocked FX-55 with no problems. The screws just hold the fan to the heatsink.
With the motherboard out of the computer gently push on the plastic pins one at a time on the top of the motherboard while simultaneously squeezing the pin points together on the bottom (use either plastic tweezers or fingernails - no metal tools!) They should pop up into the heat sink. Gently twist the heat sink to remove it and even more gently clean the top of the chip with a rag and Isopropyl alcohol (91% or better - drug stores sell it).
Have the same motherboard and the fan died after one month - replaced it with a passive heat sink - i believe it was from thermaltake ~$8.00. System still running stably to this day.