Water coolers or liquid coolers don't have water in them it's a non conductive fluid so that if it leaks it wont damage any of the parts it leaks onto. Pretty sure they don't evaporate like water and cause condensationThere honestly isn't anymore information I can give lol. The only other alternative is if the water cooling has leaked, but then idk if that would cause the glass to fog up, and how it would have found its way to all the fans.
Strange one for me