Question cpu cooling problems

[ffr2608]

Having an issue with my deepcool assassin III cooler. The first fan is colliding with the ram and not allowing the cover to close. Center fan fits fine can't reverse the flow because the fan will also hit motherboard plug cover, running a mid tower. can i go with a smaller fan for the outside one? the sizes are 140mm can I get a 120 mm for the outside one?

 

[Phaaze88]

You can't move the fan in question to the back as a pull fan?