Is a rear case fan necessary with a CPU cooler?

[ShellShock]

I am thinking of ordering a Noctua NH-U12A CPU Cooler (120 mm) for my Fractal Design Define R6 Midi Tower Case. The rear fan on the cooler will be facing towards the rear grill on the case - I estimate probably 30-50 mms from it - and I think I will have the fan pushing air out of the rear grill.

My question is, should I fit a rear fan too, to the rear grill? Maybe a Noctua NF-A12x25 PWM Fan (120mm). Is it better to have a second fan also pushing air directly out the rear grill, or will it obstruct the fan on the cooler, as the two fans will be close to each other, side by side (both pushing air in the same direction, out the rear grill).

The cooler will be replacing a Corsair Hydro H80i V2 water cooler AIO, which is over 5 years old, and is now making a horrific noise at high RPMs (not sure if it is the pump or the fan). I am bit wary now of water coolers needing maintenance after a few yeas, and I want something that should be less hassle in the long term. Also I have no need for RGB (definitely prefer not to have it), which rules out a lot of AIOs now.

 

[ShellShock]

Thanks for your reply. I wavering over air or water coolers. I have been looking at the bequiet AIO water coolers, but the one thing putting me off (strangely) is they come with coolant top-up to use after a few years. Is that really necessary? It is the kind of thing I would forget.

 

[ShellShock]

I am thinking of a 240 AIO, preferably with minimal RGB (my case is not transparent anyway). I have got a 120 AIO now which is really noisy at over 1500 RPMs (getting worse).

CPU is Intel Core i9 9900K 3.60GHz Coffeelake CPU overclocked to 4.60GHz socket LGA1151.