I'm confused; I'm not talking about mounting an AIO below the CPU, I'm talking about using the top fan slot (literally the highest point you could mount an AIO in this case).
Apologies, I simply didn't read your previous post beyond the first sentence about adding an intake fan at the bottom, and simply jumped into a mini rant, partly based on the pictures from Pjokerxp_
I think that your only real option here is to get a response from an existing user, or perhaps the best option for you, contact Phanteks directly.
Whilst I commend your desire to mod this case, and to reuse existing components, I truly wonder whether the time and effort put into this would be better spent with different options. The primary purpose of this case is to be small, and with that they made compromises that I think went too far, like so many "high performance" ITX cases.
Unless you absolutely need something this size/shape, you might simply be better off getting something like the Fractal Meshify 2 Nano, or the Fractal Torrent Nano that can use your existing ATX PSU and your 120mm AIO without compromising on the cooling/noise. there are now many great options out there for really tiny ATX cases with no real compromises, except the price, and build difficulty due to the size. e.g. the new Fractal Terra, I havent read/watched any reviews, but it is supposed to be pretty awesome, and although I have just named 3 Fractal cases, there are some great ITX cases that have all come out in the last 2-years from other companies such as Coolermaster, and some new small companies. Most of the problems have been fixed with these new designs as they are truly designed around modern hardware, but they all exclusively use SFF Power Supplies.
I only mentioned my P500A so that it didn't look like I was unfairly attacking Phanteks as a company, they make excellent products, but this for me is an awful cludge, and only exists for it's looks, rather than it's practicality or performance.
Good luck, and again, apologies for jumping the gun previously.
