Actually, I worked with HX's for many years. The heat transfer from the CPU to the heat sink, to the air stream (via a convective air flow from the axial fan) is pretty direct. If you introduce an intermediate fluid, you now have a pathway that goes like this: CPU to heat sink to water loop thru a HX (air-to-water) to your axial-fan-driven air stream. Your approach temps using the intermediate step of water are much smaller; therefore less heat transfer.
The only way a water system could be superior to air only is two ways 1) a larger water reservoir that could absorb heat for hours - would need to be gallons. 2) a phase change that drops the coolant temp well below that of the atmospheric air.
The analogy I can think of is gas engine manufacturers used an air to water to air (two complete HX's, one cooling turbo air using water, the other cooling the water with atmospheric air) evolved to air-to-air - using atmospheric air to directly cool turbo air via a single HX. ATAAC is far more efficient than ATWTA.
Sorry, just had an epiphany. I would NEVER recommend a non-phase change water cooler, it could never possibly work as well as a heat sink w/ fan. Basic laws of heat transfer invalidate water cooling w/o a phase change as an option to straight air cooling.
[Posted by: Mark1 | Date: 03/31/06 10:58:44 AM]