Could only use CCF at those speeds and Priming when I used an A/C blowing on it. And also make sure your CCF is mounted the way is supposed too I think the fan should be pointing the back of the mobo not sideways (NB). If you search this thread on my Name and Core Contact Freezer you'll see my temps on winter with tit at 1.37vcore and 4400 where topping 73oC-75oC.
The way I mounted on that pic was wrong, I had best results with the CCF mounted with the fan facing the back of the case and not sideways.