Processors got hotter, so heatsinks got heftier, and Bjorn3D check out a hefty heatsink:
The first thing you notice about the SI-97 is how large yet light it is; next, you marvel at how intricate it is. The reason why it is so light is because the actual heatsink portion of it is made up of many thin slices of aluminum soldered to the heat-pipes. This allows plenty of surface area for heat dissipation, and the quad heat-pipes help distribute the heat evenly to all parts of the fins.
[The review]