Hyper 212x vs Noctua NH-U9S for OC a 8700k

[quasiMOB]

Which one of these is a better performer for a 4.7 OC'd 8700k?

 

[zoltan.boese]

Comparing pure cooling performance the winner is Hyper 212, simply because it is larger.
If you have 160mm clearance in your case and you are keen on noise take the Hyper 212x. The Hyper has a larger fan, a slightly lower price and spins at max 1700rpm. You can read a full review on it at techpowerup.
The NH-U9S is also a great a cooler and silent under normal circumstances, here you can read a review on it. Nonetheless it is simply smaller and the 92mm fan has to spin on a higher rpm to give the same cooling performance resulting in eighter a smaller overclocking potential or high pitched noise under full load.
If you want to go beast mode, maybe check out a Thermalright Macho X2 !