I'm using a 285mm x 280mm x 19mm (13 or 14 fpi) radiator in a box with 4 120mm Yate Loon low-speed fans. I'm still working on slowing the fans a little more to bring them down to near silence. The MCP350 also needs more sound dampening to eliminate it as a noise source, though really that's not an issue for this thread. The only problem with this radiator is that it's a Derale 8000 series transmission cooler made entirely of aluminum (which is why I asked about aluminum issues in a couple of other recent threads). I got tired of looking for a copper one with these dimensions, so I got this one to use until I can find something made entirely of copper. I don't have the equipment to accurately measure the temperature drop across the radiator, or even just the basic water temperature. I tried measuring it with a cheap thermometer, but the difference was so small it didn't register. When I get time I'm planning to measure the actual voltage for each fan to try to estimate the total airflow. Currently this probably isn't too helpful to this discussion due to the lack actual temp data, but practically speaking, this radiator/fan arrangement is very quiet and appears to be coolig the water to near room temperature.
If you'd like to see pictures, etc, I posted it a few days ago on the
SPCR watercooling forum.