How quiet is quiet?

Yes I overclock the pc and yes it is very quiet, but I use 2 radiators with 6 fans running very slow. This is just for the CPU, say, 150W on load.

http://www.chilledpc.co.uk/shop/prod...roducts_id=153
http://www.chilledpc.co.uk/shop/prod...products_id=48

It's a balance between air flow and surface area. Don't suppose the base of your router is made of metal? Nice bit of Ally, even steel? Could pump the water through the section or fix a ring of copper pipe to the frame. It'll kill your flow rate but if you don't have much to start with you may never notice :)

The tube fittings on the spindle look quite small, any harm running the tube up and along the gantry?

One more thing, is any part of the spindle that contacts the water made from aluminium? I know you can use inhibitors, but life is more restful if you don't need too. Many pc water parts are made of copper, it does not play well with Ally.

CNC meets water, see pic 32 and 33...
http://www.cooperman.talktalk.net/files/27.htm