All fans on the radiators are sucking cold air from outside the case and pushing through the radiators, expelling the hot air inside the case.
That could be the problem if all the fans on the rads are intaking air into the case. You are creating a pressure differential which in this case is hindering cooling.
Have you tried running with the cover off any better temps?
Also something to try would be to pull a rad out of your case and immerse it in cold water if your temps on your cpu/gpu do not drop nearly immediately something is wrong with the flow in your loop. Talking ice cold water and it should happen within a couple seconds. If there is no significant drop off pump is dieing.
Your whole loop will heat up even w/o the pump moving the water. Takes a little bit but it will happen and it would take a long time to cool off as well.