It is not required for it but it does make it a lot easier to have one. I have the NZXT Switch 810 - (Amazon @ 149.99) when i bought it and it has so much room to work in. You can do it with single 120mm (140 mm) fans and radiators, and they do make res/pumps combos that will fit in a 5.25" bay but i have heard they get really noisy. I would recommend a full size tower for water cooling, then you can get the separate pump, res, and radiator and make it look really expensive. Plus its a lot easier to work with.