Thanks for the quick response @toolmaaker_03.
The reason is strictly aesthetics. If the radiator is mounted on the top of my case, I'd like the flow to come in from the front, where the four port holes will be, and out the back, where the single port hole will be.
So, can I have just one inlet in the front (out of the four ports) with the one in the back (setup #1)?
Im asking because I'm thinking setup #1 from my first post will not flow properly in a dual pass radiator. To correct the flow, and keep the front in/rear out configuration, I could (theoretically) tee into both sides of the dual pass radiator, and exit flow from the single fifth port from the rear (#2).
In a dual pass radiator, flow is supposed to take a "U" turn, where the inlet and outlet are next to each other (setup #3).