The radiator at the bottom ensures that the coolest air in the room, cold at the bottom - hot at the top, flows through the radiator. You'd have to ensure that the case has enough clearance underneath it for air to flow easily through the radiator.
The cold liquid from the radiator reaches the waterblocks. This hot water flows back to the reservoir. The hot water is pumped from the reservoir back to the radiator where it's cooled ready for the water blocks.
Use large bore piping with a decent pump