Your case has a spot available for the installation of a 120mm fan at the rear and in essence a 120mm radiator. Are you sure you've followed though the instructions outlined in the product manual? Try rotating and orienting the cooler to have it's tubes come from the top of chassis instead of the tubes coming from the bottom of the radiator that should take care of any clearance issues with the end tank.
It'd be a good idea to pass on your full systems specs?