My question sounds strange, I know. I wonder if it was possible to use my mac pro without the door. Back in the Powermac G5 days, we learned that the door and the plastic cover were mandatory to direct the airflow. I'm using a Mac Pro in my recording studio, and, even though it is a very quiet machine, it emits a noticable hum around 120Hz, coming from the RAM section. It's almost inaudible when the door is open, but it gets notably louder when the door is attached. Must be the side panel vibrating in resonance. I put four drives in the machine, but the hum doesn't come from there. I'd rather not leave the door open due to dust / airflow issues. What do you think? Anybody else got this problem?