our Mac Pro will perform just as well sideways in a BookArc as it will upright. In fact, an Apple Tech Note regarding horizontal placement was the inspiration for BookArc for Mac Pro. If you plan to set up two or more Mac Pros with BookArc Pro, Apple recommends placing the Mac side-by-side, instead of end-to-end. Keep the ends of Mac Pro off walls to ensure proper airflow and you’re good to go. For more info, read the Apple Tech Note here.