I'm looking for a Cooler this week, and narrowed it down to either of these 3, but cant decide which would be the best to overclock the Q6600 to about 3.20 Ghz or more? http://www.austin.net.au/ProductList/ProductDetail/tabid/104/ProductCode/CLCMRRUV8XBU1/Default.aspx or this one http://www.austin.net.au/ProductList/ProductDetail/tabid/104/ProductCode/CLCMRRV6GT22PK/Default.aspx or even this one http://www.austin.net.au/ProductList/ProductDetail/tabid/104/ProductCode/CLTTCLP0575/Default.aspx I've clocked to it 2.66Ghz with the standard Intel Stock Cooler, but it reaches 50-55c Idle and 61c at load.
i like the megahalems for socket 775 im not a fan of the coolermasters myself. also the thermalright extreme is excellent as well as the noctua d14 (probably one of if not the best out right now imo just expensive) http://www.frostytech.com/top5heatsinks.cfm for some decent reviews (some dont like frosty but at least you can really get a feel for the heatsinks before deciding)
My bud had a tuniq for his 775 e6700, which performed very well. I chose to use a thermalright with my e6700, and I usually got temps < 50 at full speed with a mild OC @ 3ghz. For my 2600k I also went with thermalright, and again don't see above 50deg. at any time, even at full blast with clocks at the 4.3ghz range. Might be able to go further, but don't see that need as nothing puts it at 100% yet anyway. Coolermaster, IMO make decent midgrade stuff, but not really quality high end stuff. On the other side of the coin though, some of the uber-razoo coolers you pay more for than you have to, if you do some research on OC forums, that will be evident Sul.