I have the same cooling fan. I run the x3 710 at 3.45ghz with a 1.47v v-core. I idle in the mid 20's and under load I get to a maximum of 44 degrees. Does the extra core really make that big of a difference?
I would make sure that you didn't put too much thermal grease on, and that the cooler is perfectly seated. Too much theremal grease/compound can actually cause the temperature to go higher since it will act as an insulator. I've also had to reseat the fan before, to get the right cooling as well. Hope this helps.