My opinion is to pick up two of those Noctua fans to balance the inlet and exhaust of the heatsink on an air cooler. This will ensure you get good temps all around instead of having to optimize the fan's speeds manually/trial and error. You will also need a fan splitter so that both fans ramp up and dial down with the signal given off the CPU_FAN header. Might I ask which Cryorig H5 you have? The Ultimate or the Universal version. The reason I ask this is due to the fact that the cooler was designed to have the fan where it is and the fan is more of a 140mm variant than a 120mm variant while the fan is placed in a push config. I'm also not sure if the cooler comes bundled with a second pair of clips to attach a fan to the cooler though...