Those sides are 330mm. Not long enough for more than 2 x 120mm fans
Was thinking about moving the radiator to the rear of the box as shown. That way I can get everything to fit. Does compromise the look of the box though, but it is at the rear so won't be easily seen.
Would work, but, through my H110 radiator, the two fans pushing air through it, (exhausting air) (they are 140mm fans), the two fans on my h110 on full speed exhausts around the same amount of air as a my rear 140mm fan on its lowest fan setting all the way up to say 1/2, so basically two fans at full speed pushing/pulling air threw a radiator exhausting, is the same as one 140 mm fan at half speed with unrestricted air flow.
So with your new design, what I would do is get a bigger radiator and then that way there is more fans at lower speed whilst also pulling in more air to them then exhausting the air out. whilst at the same time providing more cooling
From your picture there, there your intake fans would be pushing etleast twice as much cold air into the case as what is being exhausted out, and if the case is air tight, no vent holes anywhere, well they wont be doing there job as air intakes, they will just be swirling around hot air, Where as say the case had air holes or wasn't air tight and there was more intake air flow than there was exhaust air (because of radiators), then the excess air that the intake fans was pushing in, it would be constantly pushing the air in and through out them gaps whilst also pushing into the exhaust radiator fans.
In my experience, exhaust fans is more important, if the air going in is unrestricted and the air flow going out is restricted, then its just going to swil hot air around, where was if the intake is restricted by radiators as such, and a decent exhaust fan, then the decent unrestricted exhaust fan is going to be pulling the hot air away from the restricted intake and sucking it through and out. So its just a job of trial and error to find the best setup for the situation.
I remember seeing a diagram done by some of the ocuk techlabs which had two 320 radiators running back to back in like a box section of a case like the 900d bottom section for example, there was no intake, they was only exhausting air, but the exhaust fans sucked in cold air through gaps and air holes in the case, and this method was 9c cooler or something rather than trying to constantly push cold air into the two radiators, because its a lot harder for fans to push air through the radiators then for that air to seep through the gaps if that makes sense.
So for a 140mm unrestricted air flow intake fan, use etleast a 280 radiator as a exhaust, or for a 280 radiator intake, use a 140 intake etc
Btw sorry for rambling on (had a few beers)
But my 750d, my two intake fans on the front, the most I ever have them on is the lowest rpm when gaming, literally any lower on my fan controller and they turn off..
And my rear exhaust fan, I have that on 100% and my two exhaust fans on the roof of my case which are on my H110, they are also on the lowest setting, and in games my cpu never goes over 45c even at 5ghz, all of the hot air is exhausted by that one rear 140mm fan all the hot air from both of my gpus, so my two h110 fans never even intake any of the hot air from my gpu because that one fan is sucking all the hot air out before it rises that much, and because its a unrestricted exhaust, its actually drawing in cold air through the two 140mm fans at the front because they are on the lowest setting, they are amplifying the air flow through the front fans because they are on a lower speed so to speak.
Hope all this makes sense.