I have the 140 in my Define S mounted using the 120 mm fan mount it ' s mounted to my rad . I works well , but is a bit cramped and I don ' t like that it sits in front of the radiator airflow . So I actually want to switch to a separate res and pump . I can mount a res to the back wall of my case it has mounts for one and then mount the pump to the bottom which should open up some room . I couldn ' t figure out how to mount the pumpres to the back wall without running into something video card , radiator , etc . . Not sure how close the Define S is to the H 440 but I think they are in the same size class ? Take the above with a grain of salt , but thought I ' d share my experience in case it proved helpful . In hindsight the 100 may have saved room but I ' m glad I bought the 140 pump can suck in water rather quickly and even with 140 I had to be really careful not to run the pump dry while initially filling the loop .