When ambient is at an acceptable temperature, you just need ventilation. It doesn't matter how much heat you put into the air if you can simply substitute that air with ambient temp air.
You think if even is +40C?
Yep.
It doesn't matter how fast you wee into a cup, if I keep replacing your cup with an empty cup, you'll never fill it.
not quite a correct analogy.
Ventilation does not prevent turbulence. Air can be travel inefficiently that hot air got suck back into the miner .
You need to build a ducting system right at the rack. Thats the only way to control direction of air. Remember folks, you need ventilation and air direction control to be effective.
You don't if you have floor to ceiling double ended ventilation. Ie a door on one side and a door on the other....