It really depends on how much heat collects at the top of the Fractal R5 case Newbomg.
To be honest, have a try between Push, or pull with the fan setup if placing at the top.
You will only see a mild difference in C by 1 to 3c.
It really depends on what type of setup is sitting below the Rad of the water cooling loop.
SLI card setup, or a single card.