Hot air rises, better to keep top fan and replace back fan with h-50.
If you have the H50 or end up getting it, the best thing to do is to try it in multiple positions and configurations in your case and see which works best for you.
The best thing to do is have a push/pull system on the H50 on the back of the case and have the top exhaust just how it is.
well just put it in the back. i mean theres no reason not to, and if yo put it at the top, it might get hotter, even with more airflow, because hot air rises
im no expert at all, but thinking logically i would assume putting the radiator up top would put more strain on the pump due to gravity. i would think that a spot lateral to the pump would be optimal. also add the second fan. push pull.