So here's my design.
You can see the fins below the inlet barb which sit over the core of the cpu (Athlons only, including T-bird through Barton will work). The block is EXTREMELY low restriction on flow regardless of the fin design because the total surface for the water to travel through the fins is equal to the surface in the 1/2" channel.
You can also see the added surface area created by the curvey maze design. This will also cause turbulence (along with the size change in the channel immidiately following the fins) and increase cooling potential. The block will be machined 100% if possible, but if need be I can do the fins with a dremel.
I was thinking about putting dimples in the bottom of the channel much like swiftech does, but I'm not sure if that would have any negative effects - so information on this topic is appreciated especially!
Please comment and pass along suggestions. Thanks
-Zoson