OC Tools has just posted a review of a Fan Adapter that allows for an 80mm fan to be installed atop a 60mm heatsink. here's a snip:

"More CFM definitely doesn't mean better cooling. But more RPM for
something only as big as a processor heatsink, sure is effective. As
more RPM means more turbulence. More RPM though potentiates more dba.
Therefore more NOISE. I'm sure a lot of us is keeping away from the
Deltas and the likes purely because of its deafening noise. Some are
putting up with it in exchange for increased performance. Some are not
bothered at all. For those who wants peace and quiet but still would
want, well, almost same delta performance, then this is not a bad option for an upgrade."