I'm not sure if this is overkill but... Say one were to have two barbs for an add-on radiator. Anddddd... During the summer, of course they would just be straight-through with a small bit of tubing. Besides making it easier to fill when you have an internal pump, would this not be a good idea: In the winter around here, it gets coooold. I hate it. But why not put it to my advantage? My PC is very much near a wall in the basement with a small window above it. But forget the window... Why not just run some tubing outside to your outside radiator, and hook those two tubes coming from it to your extra barbs? Yes, the radiator already in the system would work against everything, but provided that you used antifreeze, the PC would be nice and cold during the winter using nature's own form of sucking heat away from warm objects... such as people, and radiators. Someone tell me this is a stupid idea before I decide to incorporate those two extra barbs into my radiator enclosure.