So here are the results fo the belgian jury. Keep in mind that this i7 970 ES CPU is a natural hothead. Even with just 1.4Vcore it can bring some older cooling devices onto their knees. A solid Phase change unit has got heaps of trouble to keep it benchstable at just 4.6Ghz. Not even talking about priming it, like we did in the chart below.

When we hooked the K2 to the CPU fan connector and allowed the PWM mode to control the fans we obtained similar performance as our humble Thermalright VenomousX cooler. The latter being equipped with two 1100rpm fans. Once we disabled the PWM fan mode and allowed the two Boost fans to spin freely we got a nice extra 6°C temp drop. Allowing the K2 to settle itself in the middle of the pack. Keep in mind that all of these all in one units, ( besides the dual rad H100 )  are allowed to suck in ambient air from the room. This makes them optimally perform, but also makes them dump all of the heat into the case. Reversing the air flow of the liquid units fans results in a lower case ambient temperature. Setback is that the CPU temps rise 2-3°C in average under load. If you are still following my reasoning, this would make the K2 cooler to settle itself on the top part of the above chart. Just behind Corsairs Hydro100 unit. Adding a 3d fan yielded even beter performance. We in fact replaced the 120mm WingBoost fan with an Antec 2000rpm fan, plus added a similar one on the other side. Though the two used 2000rpm fans are very audible and the noise level went up drastically. The small gain we got at the cost of the noise doesn't make it all worthwhile. Conclusion : The two boxed fans are more than adequate !