Globalwin have always been good about sticking large and well performing fans on their heatsinks. The increased airflow over the many aluminum fins of a heatsink can often make up for less than efficient extrusion designs.

This fan is unique in that it is one of the only 23mm thick fans we've ever seen. On the downside the 33mm diameter fan motor creates a large deadspot over the center of the heatsink.

As with most OEM class heatsinks, the extrusion is cross cut to improve surface area as much as possible. In this case you'll notice that the clip cutout is off center slightly.

The cross cuts are 2.5mm wide, and the fins taper from about 2mm to 1.5mm. While it is difficult to see from this angle, each of the fins has a serrated surface to increase turbulence, and thusly heat removal.

It is always a bit funny to see a heatsink with a fan about the same size. In this case the heatsink is 25mm tall, and the fan 23mm.

Looking at the base, which is 4mm thick you'll notice a small edge sticking out. To fit this heatsink on a FC-PGA PIII we had to remove that edge, as it stuck out too far for the heatsink to seat properly.

The base of the CPS25603-16 is less than great. Rather than a natural extrusion finish, or a milled base, Globalwin have used a very rough brushed surface. The surface really requires the use of a thermal pad, or a generous amount of thermal compound.

Surface flatness was fairly good, but surface finish is quite poor.