M-6 looks at the Zalman CNPS6000-Cu. It's a pretty decent heatsink, if you
put a good fan on it! =) Here's their review.
If you sick of your 50dBA Delta, then you might consider looking at this
heatsink. Zalman heatsinks are very unique in their design. Because of the many
fins which are spread out there is a lot of surface area for the heat to be
dissipated. CNPS (Computer Noise Prevention System) is Zalman's own trademark
that makes your computer quieter from 35dB+ to something lower, <20dB.