Here's my advice for routing coolant flow. Place the cooler at the hottest point in the system. That way you get the maximum heat transfered out of the cooler. For all of you interested in the math "Q dot equals delta T times mass flow rate". (sorry, don't know how or want to bother to learn how to enter the special characters) The pump suction should be at the coolest point in the system, just prior to the water blocks. Its also helpful to place the pump after the reservoir. That helps keep air bubbles out of the pump. So, the way that I'd route your system would be: from the pump to the water block(s), from the water block to the cooler, from the cooler to the reservoir, and finally from the reservoir to the pump again. Furthermore, if you mount the cooler in a higher position and horizontally, there will be natural convection flow through the system with the power off. I would also consider an approximately 50/50 mix of water and methly alcohol (methanol), this would greatly reduce coolant viscosity and thereby increase system flow and turbulance inside the water block. You'll also want some sufficant (waterwetter) and a corrosion inhibitor. I don't think you'll need anything to inhibit biological activity, with ~50% methanol and the other stuff. I may be wrong about that, ask somebody who has run a similar solution for several months or more without opening the system or changing the coolant. Remember to only use distilled water. Wally World carries distilled water that has also been RO and carbon block filtered, at less than $1 per gallon its cheap. Let me know if you need any clarification.