To me it seems the way you are routing the tubing could be hindering getting all the air out of the rads as you are trying to push the air down the tubes which will not happen, that GPU block is not helping you one bit as there is only the 2 downward facing ports on it by the looks of it?
I would try, res/pump/GPU/120/CPU/240/res, once in that order, if it's possible, unplug the power to the board and components so you can fill it up with nothing but the pump running, lay it onto the back panel of the case so the res is facing the sky, then fill it up, that way all air should be able to get out and into the res.
I would try, res/pump/GPU/120/CPU/240/res, once in that order, if it's possible, unplug the power to the board and components so you can fill it up with nothing but the pump running, lay it onto the back panel of the case so the res is facing the sky, then fill it up, that way all air should be able to get out and into the res.