Well, I'm milling out a waterblock for my northbridge at the mo. I've measured the mounting holes at 60mm apart, and the block is going to be 40x40mm square. I've included the layout of the waterblock here. The reason for the s shape instead of the centre inlet/corner outlet design is for mounting ease. I'm just going to get a bit of brass, a couple of nylon bolts and make a brass backplate (foam insulated of course) and brass top plate and screw it on. I'll post a few pics along the way. The template I'm working on is glued to the top of the block, and the lines are just a guide for the 3-5mm channels I'm milling.