This effectively increases the surface area that can be applied for heat transfer. We all should know by now that increased surface area equals more efficiency. Think about this, your intestine has millions and millions of fissures. These fissures allow for more efficient uptake of nutrients into your bloodstream. Another attempt to increase the efficiency of the heatsink was made by adding copper to the PAL's base.
Copper is more efficient at transferring heat, flat out.
Alphas added the copper in an effort to further increase the heat transfer potential and improve performance. Both of my Alphas came with a YS Tech 60mm x 60mm x 25mm fan that pushed 27.5 CFM of air. My fans came tailed with a three-pin RPM sensing connector for attachment to your fan header on the motherboard. The installation of these heatsinks isn't exactly easy. Alpha supplies a clip with which you press down around the protruding tabs on the socket.