Another consideration I had to deal with was the sheer amount of heat generated by these machines as well as their inability to move air very well. The Mac Mini was designed to be a small quiet desktop machine. It was designed to have access to open air and not be stacked or crowded. The Mac Mini’s design causes us 2 problems, 1. The fans are small and underpowered and 2. the design relies on the case as a large aluminum heat sink. If the fan can’t move air and the case is stuffed in a rack with 159 of it’s closest friends, that means we have to help the air through the cabinet and across all of those cases. I have done some experimenting with some fans designed for these racks, but none of the models met our criteria (220v and a ton of air movement) so I decided to do things my way, and build a solution. My design started with a high volume DC electric fan, it looks just like one you would find on a car radiator, because it is from a car radiator!, I sourced a 220VAC to 12VDC @ 40A power supply and a 40A DC motor controller. Once connected I had the ability (at high speed) to move so much air I could blow my office door shut from 6 feet away, while at lower speeds I was able to move plenty of air and have a nice quiet environment. I decided that 4 fans attached to the inside of the front door pulling air into the rack was sufficient to move air across all of the shelves, so I built the door in the pictures. You will notice the door is all self contained with the power supply, motor controller and fan all mounted together. The only thing the door needs is power from within the cabinet and it uses a standard 220v power cord.