I went to the coolermaster web site and found no info on the units cooling ability.
The Arctic Cooler Freezer 7 Pros cooling ability is listed as
Thermal Resistance 0.17°C/Watthttp://www.newegg.com/Product/Product.aspx?Item=N82E16835186134
It's about the same price as the hyper and is known to cool well. When info regarding the cooling efficiency of a product is not given on the web page of the cooler, I take it off my buy list. That is unless a site like HardOCP has reviewed it and given the info in the review.
I have found that Arctic Cooling makes an excellent affordable product.
I run 5 systems and they all have Arctic cooling inside.
Also what is the ambient temp there the computer is located?
Your e6400 should not be so hot, even on the stock cooler.