As labbbby pointed out, condensation is related to relative atmospheric humidity, which in turn is related to ambient temperature. In temperate climate zones, relative humidity is pretty variable, depending on season, weather conditions, proximity to large bodies of water, and so on. In winter, most people heat their houses. Also, the colder the "natural" ambient temperature, the drier the air is.
But furnaces produce extremely dry air, which is why most are equipped with a humidifier. I have seen ranges of 25% to 40% relative humidity recommended in some furnace/humidifier manuals. The reasons given include, but are not limited to, human health and structural integrity of the house. Healthwise, the humidity makes breathing easier and maintains moist mucous membranes, which trap bacteria better - less colds. From a house structure perspective, it is not good if the lumber gets too dry, or so I am led to believe. High relative humidity levels can lead to condensation in a cooled system.
Overcooling a system can lead to problems due to differential shrinkage rates. At the same temperature, different materials shrink or expand at different rates. Metals vs plastics vs composites have different physical characteristics, which can cause serious physical strains at best. Differntial component shrinkage rates can lead to significant strain on the MoBo and components attached to it.
And this is before we get into the issue of condensation on the componts of an agressive coolling system. And where is this condensation on the tubing and cooling blocks going to go, I wonder.