i'm running the stock hsf from a 6750 on my e4500@2.8 at stock (1.75) voltage... i get up to 55c with the house at around 70f right now... i didn't try the stock hsf that came with the e4500, it's all aluminum and the 6750 hsf has a copper core...
odd thing about the stock 6570 hsf is that the outside of the fins never feels hot... my tuniq 120 gets nice and warm on my x2 when keeping it at the same temps... i'm pretty sure that the stock intel hsf is making a ok connection with the chip, but no way is the connection pressure anything like on the tuniq...