Here's a link on water cooling
. You can Google "water cooling" and browse dozens more.
From your listed specs you have a really sweet rig. So, pragmatics first. If your system is running hot and sounds like a chopper lifting off then water cooling is a logical next step.
If you don't have over-heating and excessive noise problems and want to add water cooling "just because" that's not a bad reason either.
If it were my choice I would use a kit in the first example and try to rationalize a case cooler in the second.