I am currently building a µITX pc for my Brother and its all kinda finished. Case i am using: MSI Nightblade The only thing i cant quite fit in there is the Corsair H75 Closed Loop Watercooling because there is not really any space for the Tubes.
They use proprietary permanently attached fittings. Even if you managed to get it off.. You wouldnt be able to get a perfect seal.. and it will most definitley leak. Honestly at this point you can get the swiftech H series and they are really just custom loops in a AIO form factor and are expandable... thats much more worth it than ruining a good AIO for means of making it fit.