Water cooling doesn't provide any real advantage in silence, I find. Pumps make a little noise. Turbulence occurs wherever liquid flow moves through blocks or is forced from one hose size/direction/geometry to another. There are sometimes little gurglies in the rad and reservoir. And all the same fans, always the same fans, they're just moved around to different places (usually right up against holes in the chassis, where they push all the noise out along with the heat).
Coolant needs to be replaced now and then, blocks and hoses need to be scrubbed out, water cooling requires more active maintenance than air cooling. I find it can be a real bother if needing to constantly tinker and swap parts. Critical failure (dead pump, leaky fitting, dry res, etc) in a water cooled system means all your parts are covered with hot blocks of metal, maybe also swimming in steamy hot liquid, and quickly subject to serious thermal or electrical failure. Leaks can happen, and that is indeed a Very Bad Thing, but the risk is minimal if proper care is taken.
Big air coolers can be surprisingly effective. It certainly doesn't look as elegant. There are often compatibility issues between a CPU cooler and adjacent motherboard components, memory, and expansion card. GPU card widths unavoidably occupy two or even three slots each. Small form factor cases are often off limits. Dangling a massive chunk of metal right off your mobo socket can cause concern, especially if the computer is frequently moved around. Critical failure (dead fan, etc) means cooling on a single part becomes much less efficient, but even then there's still a large passive heatsink doing what it can.
Neither of these cooling approaches can take more heat away than the computer produces. Robust liquid cooling can outperform air cooling and allow a lot more overclocking/thermal headroom, if you don't mind the noise.
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