The heatsink is the same as the heatsink used in the first AMK-SECC80, which is to say it's very big. There are lots and lots of pin fins on this heatsink. 250 of them! The sink has slots cut into both ends of the heatsink like the coolers from Global Win and TennMax units. This aids in the cooling of the L2 cache in the Pentium II/III CPU. Because the first SECC80 came with such a weak fan, those slots didn't do much. However with the high power YS Tech fan on the cooler, it's another story.