best is to blow the air OUT of the room, no need to pump in fresh air.
Sorry but thats not true , fresh air must be pumped to cool down the machines , it's a simple rule if there is exhaust there must be intake to fill the hot air pumped out with cool fresh air.
Of course it's better to have a push-pull setup if applicable, but if that's not the case it's much better to just push out the hot air, than to pump in fresh HOT air from outside (summer is coming).
Wind is our friend if available