What are the dimensions of the room (LxWxH) and dimensions of the windows and quantity?
There's a lot of HVAC calculators out there for air exchange CFM requirements, if you want to do it right this is how you do it.
Having a pile of miners running with the air just blowing willy-nilly in the room is going to create hot and cold spots, you want to read up on fluid dynamics, turbulence, what causes dead zones, and visualize the airflow in the room.
Put the big furnace style blower as an exhaust fan in one window and an array of cheap box fans to keep the air moving from the inlet window, if you can create a wind tunnel effect across the miners you will be better off, but I don't know the layout of the room and what we're working with here.
Draw it up or post pics or both.