I will not guarantee an OC of 4.0, furthermore, that kind of OC is pretty extreme. If any air-cooling is going to support that OC, the two i listed before will support it, but again, it's all dependant on the motherboard capabilities and if the CPU itself can reach that speed. ALL CPU's & Motherboards are different.
In my opinion, go to 3.6, that should support the 5850 no problem and it will mitigate possible damage to the CPU/Motherboard as it is a moderate OC...