AC is a waste of electricity unless you have free power, your exhuast fans need to be ABOVE your rigs not in at the same level and you also need to make sure your room is somewhat presurerized
you can tell this by when you open the doors you feel the suction of the exhaust fans pulling heat up.
I have 30 rigs in my garage with only 1 of six exhasut fans going and my temps are like 30 degreees in winter, fall with three fans going like 60
semantics..... lol. But yes; exhaust at high in the ceiling as possible, and more is better. Just keep adequate inlet CFM as well, and away from the discharge zone.... ideally, in from one side/bottom of room, out the opposite ceiling; and a few fans to keep the rest of the air in the room turbulent.
AC usually doubles or more the electric cost. Its a pretty astronomical number.