Im currently building a brand new computer, and i want it to be water cooled with fans, the case i have, its all ready presetup for watercooling, and i would like to add some intake and exaust fans. but i was worried that this might be over kill, i like to have a nice cool machine, but im thinking that haveing a pc to cool might cause problems..Any ideas/suggestion on this?

nah as long as its not cold enough and exposed to outside air (which could cause condensation), you really can't overcool a pc.