Thanks ! Do you have pics of your build ?
I have to update the first post with the case final specs :
Total dimensions are h.355 x l. 260 x p. 146 mm
Volume : 13,48 L.
Max GPU length : 280 mm.
I realized I didn't actually have any photos of my finished build anywhere - guess that's what happens when it doesn't happen in one go, but is rather a piece-by-piece upgrade over a couple of years. It lives in an NZXT H200i (yeah, I know, it's large for an ITX case) and looks like this. Should probably pop off the glass and do some dusting, didn't notice that until I turned on the case lights for the photo
It houses a Ryzen 1600X in a Biostar X370GTN, an EK 240 CoolStream PE (38mm) plus an old 120mm rad I had lying around (about 30mm thickness IIRC) both with 25mm fans (a Nidec GT 1850 on the 120, BeQuiet SW3 1450s on the 240), an EK-XRES 100 SPC-60, a Fury X with an EK block, an EVGA G2 750W (yeah, major overkill), plus a bunch of EK ZMT tubing and various fittings (IIRC a mix of EK, Bitspower and Barrow, though there might be some AlphaCool stuff in there too). I'm happy with its performance - it never gets loud, still keeping the GPU around 50C and CPU around 60 while gaming. Okay for 400W of wall power draw/~350W heat output in a restrictive case.
At 26.1l I was quite close when I said you were around half the volume. My choice of case was a compromise based on budget, availability and compatibility with already owned parts - I bought the Fury X in 2015 (wow, nearly five years now!) which also necessirated a PSU replacement as my old one died during stress testing of the new GPU (it was from 2008, so had served me well), the motherboard+1600X+RAM in 2017, and the case in 2018 - before that everything lived in my old Fractal Define R4. And of course the PSU dying was too early for there to be any good <500W SFX(-L) units on the market, at least that I could afford, meaning I got stuck with an ATX unit. I could have fit the PC into an Ncase if I had the money, but importing one to Norway would have cost me around 3-4x the H200i, and I would have had to buy a new high-end PSU on top of that, not to mention even more specialized water cooling hardware as neither my pump or reservoir would have fit.
Looking back I don't see any way I could have achieved more SFF-ness with my available budget (outside of DIYing a case from MDF or some such), but there's definitely lots of room for improvement. The tubing runs are a bit sloppy (mainly due to me not being very comfortable installing the very stiff ZMT tubing), and with some more angled fittings I could probably flip both rads for some much cleaner runs. I might be looking at a major system upgrade this year (might get it funded through work), but I doubt they're willing to subsidize specialty cases or water cooling hardware, so for now I'll probably be sticking with the case, even if it's not what I really want. I'll just keep sketching out improved case designs until I can actually get one