What wattage are the graphics cards and cpu, what temperature do you want them to stay below, and do you want the system to be able to run flat out for days? If it's the thing in your sig then you're going to struggle with anything smaller than a triple.
If the system rarely runs cpu and gpu flat out at the same time, you can get away with fewer radiators. If it wont be running flat out for more than a few hours at a time, the heat capacity of the system will let you get away with less.
If you're looking at 600W heat dump and want it to be able to run under that load for 12 hours or so, you'll need a much bigger case than if you want 300W heat dump for an hour and a half.
edit: I see from your build log that you're currently using a 240 and a 120 - that suggests adding at least another 120 to keep temperatures in the same ball park. I think your question amounts to "what's the smallest case that holds four 120mm radiators in some combination and a m-atx motherboard". Sadly I don't know the answer to that. I have roughly that cooling capacity in an Akasa Eclipse, but there really should be smaller options out there.
