This is news to me, but I guess logical. Mounting the radiator of an AIO at the bottom of this case (or any other case) is a bad idea, at least according to Gamers Nexus, who specifically reference the NR200;
https://www.youtube.com/watch?v=BbGomv195sk
May explain why the AIO mounted in my Dan A4 cools so poorly, and one core runs 15c hotter than the others, even at idle.
Just finished watching that. Long video, so brief summary:
The problem stems from the pump/block being the highest point in the loop. Any air in the loop rises and congregates in the pump/block. This would be a problem whether using a regular AIO, modular AIO, or a full custom loop; air will always rise to the highest point, which you don't want to be your pump or block(s).
If you're using a regular AIO and mounting the radiator at the bottom (per NR200P with glass side), the pump/block will be the highest point in the loop. Air will congregate in the pump/block, which could have anything from a marginal performance effect (if there's little air in the loop) to a significant one (where there's a lot of air in the loop and the pump is running dry). This can also put a lot of strain on the pump, as many designs aren't intended to run dry (Asetek being a named exception). Even where the AIO has little air, it will run louder. And over time, fluid will evaporate from the loop, causing the above problems to get progressively worse.
One possible solution would be to use a modular AIO and add a 92mm rad on the rear panel. As long as the tubes exit from the bottom of the radiator, the top of that rad will be the top of the loop.
Not hugely relevant to NR200, but if you're mounting a regular AIO radiator at the front of the case, make sure the tubes exit from the bottom. This is less a performance issue, and more a noise one. Also make sure the other end of the radiator is the highest point in the loop (this is where you want air to gather).