Mounted one above the other, they will add up to more that 360mm. Even with the one 120mm turned on its side, they will still add up to more than 360mm, because the "240mm" radiator occupies more length than 240mm. Additionally, it is a bad idea to turn a AIO/CLC radiator on its side anyway. A AIO/CLC radiator is designed to have the hoses at the lowest end of the radiator so that air can be trapped at the top of the radiator; otherwise you will have issues with cavitation, pump noise, and reliability.
If you could turn a 240mm radiator "on its side" and then mount another 120mm radiator below it "on its side", I think that would fit. It would be impractical. It would be a bad idea. I doubt there are many computer cases where this would be an option. But, I think that is the only way your idea could be adapted in a way that it would "work".
Stacking them is an option. It wouldn't be optimal, but it's an option which would work. If I had to stack them, I would stack the 120mm onto the 240mm with the 120mm at the highest point of the 240mm. The 120mm radiator would get the slightly cooler air, and being at the top of the 240mm radiator would mean that it would be at the mid point of the 240mm radiator's loop from bottom to top and back to bottom, so the 240mm radiator would still have 120mm of lower area to cool down with slightly cooler air prior to its outlet. This would solve the dimension issue and hose orientation issue. Only problem is that the total thickness dimension may become an issue. ... Though theory would say that how they are stacked would make very little measurable difference.
post edited by ty_ger07 - Monday, April 01, 2019 4:15 AM