Originally Posted by rheicel
I think depending on the set-up. If you have multiple rad, it makes sense to be careful with the arrangement.
Example of two rad that will make a difference:
In the arrangement above, CPU will make the water hot and before it passes the GPU, the RAD will dissipate some heat. Overall water temp will make no difference in this arrangement, but the GPU temp when arranged in a correct manner will be a bit cooler compared to the loop going from CPU straight to GPU.
I think you'll find even in this case that the water temperature remains the same throughout the entire loop.
Of course this would be easy to prove / disprove by placing temperature sensors at any points of the loop and comparing the readings (I would do this if I had the equipment).
My guess is that there is an unnoticeable (or, at the very least, unnotable) difference between the readings.