Thank you for your help.
I have been testing with the stock and the ACF13 coolers, and this is the result.
As you can see, the stock cooler can keep the cpu temp at the limit, 60ºC, but it seemed like it was going to take off at almost 6000rpm... :
The stock cooler has a clip system quite hard, but the ACF13 has a screws system, so this time I tightened them a lot:
It seems that it's not enough to tighten them, you have to do it in "Arnold mode".
Even so, it "only" can keep the temp at 55ºC, and I am dissapointed with it. When I bought this cooler, I though that the cpu could be at 40-45ºC. May be this cpu model has too high temps.