Smooth side

Rough side

The rough side is the one that's curving inwards. This means that the air molecules will mostly strike the rough side of the fins. Now, I've read somewhere that creating some air turbulence may increase the heat transfer efficiency. I'm no thermodynamics expert so if anyone can enlighten us on this issue, please feel free to do so in the forum.

I asked Bitspower to shed some light on why they implemented the rough surface on one side of each fin. Their reply was simply, "The rough [side] has more surface for heat dispersal by air."

On closer look, you can see that the rough surface was manufactured through some sort of "chiding" process. This can only mean one thing - the whole heat sink was really made from a BLOCK of aluminum.

Also, the curvature of the fins makes the heat sink look as if it's tilting over to one side. It's looks awkward and yet also rather cool and unique at the same time. One thing's for sure, it will attract its share of peeks and stares from other users!

Fins comparison

Another interesting feature is that because the whole heat sink is made of a single block of aluminum, there's no thermal resistance between the base of the heat sink and the fins. In other words, there's no resistance to the heat flow from the base to the fins.

Another interesting thing to note is that the NP60D's fin thickness is different from that of the NP80D. The fins on the NP60D are much thinner than the NP80D's. This is actually expected due to the denser fin count on the NP60D.

NP60D on the left, NP80D on the right.
See how much longer the NP80D is!