Thanks for measuring and the detailed answers! So the dual superslim rad with a mDTX is an option, tight but an option. Well, that sounds excelent as those XSPC rads, according to reviews, actually outperform in low speed some of the best 30mm rads (EK, Alphacool...) and even get on par with HWL GTS at low speeds. Speeds here are the key, as for a setup like that, the noctua 15mm fans are mandatory and those reach up to 1800 rpm, so ideally I´d keep them at 1200 rpm (the speed where the XSPC TX series outperforms other 30mm radiators). If the point is cooling both the CPU and GPU, that should be more than enough and even have some headroom for overclocking (no reason to buy an expensive Crosshair VIII Impact if you´re not overclocking).
For the PSU I thought about going for a Corsair 750W, so that should power the whole setup and keep a reasonable headroom for overclocking. There are 1Kw PSU planned, so I see no point on going SFX-L if you trully need that amount of power (cooling off such amount of energy waste in a classy way is a different story, of course). Speaking of the PSU, this case is a great excuse to order some custom cables so the lenght becomes as small as possible thus making the management easier (standard PSU cables will quite long for a case like this).
The key for this arrangement is getting a pump as compact as compact as possible. Fancy reservoirs and pumps like the Heatkiller or the VTX are too big as they are around 70x70, so you are aiming for something smaller, correct? I don´t know if expanding tall should be an issue (from the images posted, it shouldn´t be) so I have considered options to attach the reservoir to the pump and save the reservoir up top.
Well, I can see a couple options from Barrow and Bykski or a combo of Bitspower (here, here, here). On those cases, if EK decides to sell the VTX by itself, it will just need a swap on the pump itself. Same goes in the case of malfunction of the DDC in case you need to swap it. All the linked products are 62x62 in surface, only hight changes. I tried to provide examples with several inlets/outlets so, due to the position of the pump, you could also set a drain port due to the low position.
Last but not least, what are the exterior measures of the case now in its current shape?
