Turbokeu:
Some more test results (article coming to Procooling in next day or two) with a more restrictive 3/8" loop. This loop has 2 Black Ice Micro radiators, a Swiftech MC50 GPU block, a Swiftech MC5000A waterblock, and the 3 valve fill and bleed kit all with 3/8" ID tubing. The 1/2" loop is a Dangerden Maze4, Black Ice Extreme, a 1 gallon res, and 1/2" barbs and hose (as before).
http://www.procooling.com/~phaestus/...lowresults.jpg
When graphed over P-Q curves then it looks like this:
http://www.procooling.com/~phaestus/temp/flowcurves.jpg
So 4 L/min is probably about right for MCP600 in your rig.