My target in spring this year was to reduce noise of my workstation.
I could, maybe I should write a longer paper about noise reduction and cooling. Including to explode myths about cooling paste. But for the last one some measurement effort was needed to put it onto more scientific feet. I don't know yet.
However, without going too deep into details:
The idea was:
With watercooling more fans are possible. With more fans I could reduce the rpm of each, thus reducing the noise.
What you see is a 
be quiet! watercooler I modified slightly: 6 140 mm fans "
Silent Wings Pro" (those things are really silent) in push-pull config.
The result was actually a noise reduction, but not as much as I hoped for.
Errors I made (didn't really scientifically studied all details in the first place - the whole project was part playing, of course):
- The fans need some minimum rpm to do a steady job, and not running up and down in waves. (The graph rpm vs liters air per hour of a fan ain't linear but exponential; you need to run it at least ~50% to get any useful airflow at all.) So of course the fans don't run totally quiet at all.
- In underestimated the noise of the other devices: My Mainboard has a small fan, too. And of course the GPU.
For some of those is also watercooling available, but only for the premium products. Unless I win the lottery I will keep the church in town.
 
There are also a few complete passive CPU coolers available, but this ain't help with the GPU issue.
And of course there are really quiet machines with no fans at all (Beware! There are some computers advertised as 'fanless' while in fact they are not.) But those are either pretty low on computation power, you have to dipense on many things like not having more than one storage drives. Or they are very, very expensive.
So, bottom line:
With watercooling you can reduce noise a bit.
All you mostly get is a pretty cool machine.
At low loads my CPU is at 27..28°C, and when compiling larger jobs from ports for example, temp does not exceed ~55°C.
Nice.
But that was not my target. 
