thermalright HR-01 Plus got one on my own Q6600 idles around 36 36 32 32 at 3.6ghz 1.487vroom temp around 25
Id look at the sunbeam, excellent cooler, your OC depends on so many different things, mobo and bios as well as each batch of chips being different, but you can aim for 3.4 give or take 0.2