__________________ Ren: Now listen, Cadet. I've got a job for you. See this button? Ren: Don't touch it! It's the History Eraser button, you fool! Stimpy: So what'll happen? Ren: That's just it. We don't know. Maybe something bad, maybe something good. I guess we'll never know, 'cause you're going to guard it. You won't touch it, will you?
Most people use computer case fans, the 120mm variety, to ventilate existing furniture AV cabinets. You can buy them pre-rigged for that very purpose or you can hook up your own if your handy with wiring.