Brushless fans generate less electric noise, meaning better for computers. Next, examine what kind of voltage and what kind of power draw it has. 0. 10 Amp model. Your Amiga should be able to generate both 12V and 5V. DC, by the way. Look at how much air it blows out.
Air flow is measured in cubic feet per minute.
Compare numbers and prices. It should end in two wires. Some may have a convenient header block. Let them show you a demo unit. Feel the air coming out.