It's counterintuitive, but AIO liquid cooling is often louder than a comparable fan cooler. It takes a lot of static pressure to force air through a radiator,

It's counterintuitive, but AIO liquid cooling is often louder than a comparable fan cooler. It takes a lot of static pressure to force air through a radiator, and such radiators are definitionally mounted near some kind of air intake/outlet so there is usually very little noise dampening available. Also, AIOs usually have the cheapest parts available (pumps/fans) and are lower quality than you would get from a (much more expensive) custom setup.