My rack used to sit in the middle of the basement. It was loud and made the space look messy, so I moved it into the closet under the stairs. It fits with room to spare, and there's a gap at the back for running cables.
The closet has a hidden vent hole in the upper right corner. I mounted a small fan there, and with the door shut the temperature dropped about 10 degrees. I lined the walls with acoustic paneling to cut the fan noise.
