[Cathar]

jungle, your grandad is a smart guy who knows his stuff, but waterblocks are starting to progress beyond the broad-scale statements he's making, with the newer ones really starting to fine tune and eke out possibly more performance than he's decribing.

The Atotech MC1 is perhaps the closest commercial example to what gramps is talking about. It is basically a stack of copper plates that have been soldered together with chemically etched 0.2mm micro-channels in the plates. When the plates are all soldered together it forms a "block" of copper with hundreds of 0.25mm squared pin-holes through it.

The MC1's performance, about 2 years back now, arguably matched by the combined early micro-mini channel/impingement blocks (ala. White Water) for which the same basic design is a fairly common design in use today exemplified in a whole host of blocks, most of which outperform what the MC1 offered.

The copper's thickness is now an issue too, and cannot be trivially dismissed as being a good enough conductor. True, the resistance of the copper is typically smallish in comparison to the thermal paste interface, but with the advent of properly lapped waterblocks and high quality thermal pastes, it is no longer something which can be dismissed off-hand. Thicker copper base-plates allow for wider heat-spread to the convection area typically resulting in better low-flow performance but sacrificing somewhat the available gains which can seen with higher flow-rates. The reverse is true for the thinner base-plates, where low-flow performance tends to fall away, but higher flow rates generally allows them to surpass the thicker base-plate designs.

The simple side to side high-water-flow-through-channels approach will provide highish end performance compared to today's top-end blocks, but it is seeming more clear that some degree of impingement is a more efficient way of stripping back the boundary layer to eke out even more gains. This can be witnessed in that there are almost no top-end blocks on the market today that do not utilise some form of impingement.

Some of the super-refined micro-channel blocks that very carefully balance off pressure-drop vs performance are holding their own very well though. I'm personally of the opinion thought that pure micro-channel blocks, at least in terms of the balance of presssure-drop vs performance, are getting pretty close to the limits of what they can offer, especially for very high heat load modern CPU's. There do exist a number of exceptional examples though that show close to the full potential of what micro-channels can offer, and it is very impressive.