Air cooling is not as effective as water cooling,

It’s not that simple because air cooling in pcs today means a heatpipe. A heatpipe uses fluid (such as water under a vacuum) that boils at a low temperature. The phase transition of liquid to vapor transfers hundreds of more times heat than simple conduction of cold water running over the CPU.

en.m.wikipedia.org/wiki/Enthalpy_of_vaporization

It’s how refrigerator compressors work to cool things so effectively. The genius of a heat pipe is it works without an electric compressor ( this limits it’s cooling ability but it’s still genius).

So a heatpipe CPU air cooler with a 120mm radiator will outperform a water-cooler with a 120mm radiator in almost every situation. The advantage of water-cooling is you can make that radiator huge (280mm is typical today), and place it on one of the side/top panels of the case where air is cool instead of deep inside where the air is hot.