Water cooling is often contrasted against air cooling, but really, water cooling is just a middle man inserted between the heat source and normal air cooling. Water cooling still relies on a rad, fins, and air moving over them to remove heat. The water part for water cooling really only replaces the heat pipes of what we call normal air cooling. Has anyone done a detailed study on why water cooling performs better?
1. How much of "water cooling's" superiority is explained by just having more air to metal surface area on a radiator vs a standard heat sink?
2. Or is it really the water that explains the performance? Does it have higher thermal capacity against the heat pipes used in air coolers?
3. How much of the apparent performance is simply because heat pipes are typically 5mm whilst we pipe our machines with 10-12mm when water cooling?
4. Is it the micro channeling that delivers the lions share of the benefit that can't be done with closed system heat pipes?
It just seems to me that water cooling is an addition to air cooling, not something it should be contrasted against. Eventually, all the heat has to be dissipated into the air since that's the environment we live in. Perhaps it's more accurate to contrast water cooling to heat pipe cooling. In which case, I'm not sure I've seen anyone ever explain in a measured way why it's superior. Just a geek wondering why things are the way they are.
(I've left this question on reddit as well but figured I'd get more insightful answers here) Update. Got standard acidic answers from reddit. With the insights here on this forum combined with my own here's a summary. A. It has nothing to do with the heat capacity of water vs. air/copper/etc. Both a custom water loop and a Hyper 212 Evo have air as the final destination of the heat and use water to get it there. It's true water has higher ability to store heat than air, it has nothing to do with water cooling's superiority to a standard air cooler like a 212 Evo.
B. "Air cooling" is a misnomer since both a "water cooled" and air cooled rig eventually dump heat into the air. The real comparison's we talk about, taking a standard 212 Evo as example, is Water Cooling vs. Heat Pipe Cooling.
D. FYI all "air coolers" like a Hyper 212 with heat pipes have water in those heat pipes. They aren't just copper tubes.
C. I believe the two biggest factors accounting for the superiority of water cooling are: i. The surface area contact of the fluid with the heat block. Looking at a water block, the "micro-channels" provide much more surface area for the block to dissipate heat to the fluid than the walls of a heat pipe dissipating to it's own fluid.
ii. We push water through our custom loops with a pump whilst a heat pipe relies on (presumably slower) convection.
Common reasons given for why water cooling gives superior performance that I believe are wrong or overstated:
F1: Heat capacity of water vs. air. (True that water is higher, false that is has anything to do with water cooling)
F2: Surface area of a radiator vs. a standard air cooler. I suspect radiators do afford much more surface area to dump heat, but I don't think its a significant factor compared to the two mentioned above. Samp our your huge rads for a skinny 120mm and I doubt your rig will collapse to performing like a 212 Evo.
F3. Rads are on the outside of the case and aren't dumping heat into the case. Not wrong, but again, minor to no effect. A nice high-flow air cooled rig isn't hard to achieve. I seem to recall exhaust vs intake rads or putting rads back to back also having little to no effect on performance.
I'd love to see a tech tip on this since even big youtubers, "pro"s and intelligent people in these forums all seem to point to ideas like "water heat capacity vs air" and other reasons that just don't stand up to a few minutes of thought.
