Check this homemade WB out

[Martinm210]

I just can't see how 4lbs of copper with close to 50 fins could perform so poorly, when it works with air alone and no water?

That's what most of us coming from air over to water think. It comes back to the difference in mediums. Water is so efficient at transfering and storing heat that the copper itself becomes an insulator of sorts in comparison(it can't move heat fast enough at great distances to keep up). This is also why copper bases are so thin. If mass and surface area was the key, water blocks would look like air cooling tower sinks.

Thermal properties of water is just so different all that matters for cpu/water exchange is basically the bottom few millimeters of copper that is in contact with the IHS over the cores. The rest of that 4 lbs of copper is only contributing to the water/air heat exchange. That water/air exchange is where size matters...and that's because air technically is an insulator, it sucks at heat exchange and it also sucks at storing heat especially the storage piece.

And I'm no expert, I dropped thermo when I was in college many years ago, my experience comes from my own random experiments. I suppose a lot of block design today is a result of experiments though...there are too many variables to pin down theoretically. If you could optimize using theory alone someone like bill adams or cathar would have already done it...

Anyhow, don't give up...its a neat idea and something different is always cool. Maybe a standard copper waterblock with heatpipes soldered to a more conventional aluminum hsf would be another idea to the same hybrid idea. Pumps do fail and not everyone wants massive radiators.