You have to get rid of the hot air, and bring in fresh air. S9's generate 90 cfm of air flow each, if you can capture the hot air you can channel it to an exit point. Dont try and cool the room with an air conditioner, its better to use that power for miners. Evaporative cooling works, but it raises the humidity and can cause corrosion, although s9's may only be viable for another 5 to 8 months. If you have a ceiling vent you might try arranging in a circle and vent the air up, that takes advantage of hot air displacement, I have seen a number of large setups do that.

just my $.02