Originally Posted by HexagonRabbit
Um I'm gonna have to disagree with you there.
I idle around 26c-29c with my windows open @ 3.9 and Overwatch, Forza, D3, AOTS of 44c.
IBT of around 60c. The highest I've seen my CPU get was 71c and that was with the lowest RPMs on everything (pump and fans in push/pull) with IBT, Cine, and Time Spy running with the windows closed at around 76f-77f ambient temps in my room.
The only time my fans spin up anymore is if my windows are closed and I'm doing SEVERAL things at once. I seldom hear my pump anymore. Quite a change from my old 9590.
Speaking of IBT. My passes @ 2933 14-14-14-34 are about 35 seconds slower than 2400 15-16-16-36 on very high.
This gets complicated and requires a discussion beyond just temps. A wood fire in your fireplace and a match burn at essentially the same temperature but the amount of energy coming from the fireplace is significantly more.
An air cooler uses metal (excluding some heat pipes which aren't significant in this discussion) which has a limited thermal capacity - it heats up quickly and conducts heat efficiently. The limitations are the surface area of the fins and effectively transferring all that energy to the fins to dissipate it. A side issue is removing the heat from the case. They work quite well up to a point but those two limitations are real. A side benefit is the low thermal capacity means they cool down quickly once the load drops.
A "water" cooler (often some form of water/glycol mix) has a much higher thermal capacity and as a moving liquid is much more efficient at move the thermal energy away from the source. For short spikes, it can be much more effective at suppressing thermal spikes. As a liquid, it can disperse heat much more evenly through the radiator allowing for more efficient dissipation. It is also a lot more effective at removing heat from your system versus simply removing it from the processor (CPU or GPU). Inadequate radiator designs can hamper cooling which is likely the primary reason for complaints about AIO's since the fundamentals are the same. An AIO with a quality radiator can perform perfectly well.
So water cooling definitely has more potential for heat dissipation. There's a reason it's used in Automotive and other situations where there's a need to remove significant amounts of heat. Whether it is "better" than air really depends on the specifics of the system needing cooling - the thermal load, the system design, etc.