FYI, Apple seems to have removed all support articles that relate to clamshell mode. No reason given, but they do not even show up when you use the "show articles not being dated" filter.
It may be due to conflicts with information in this Apple article:
Keep your Mac laptop within acceptable operating temperatures - Apple Support
specifically this part:
Closing the lid while the computer is not sleeping seems to constitute "putting something over the keyboard."
My concern with clamshell mode whether if running on battery or wall power is temperature. 13-inch Macbook Pros draw air in through the keyboard and hinge. Larger screen sizes models have side vents between the bottom plate and the mail chassis that let in air.
However, all Macbook Pros expel heated air though the hinge. Blocking the exhaust will overheat a computer as fast as blocking an intake—I've tested it.
If you "bookcase" the computer vertically and one side edge of the computer is against, say, the back of a closed bookcase or desk shelf, you've reduced cooling capacity by 50% with 14+ inch model. Open-back shelves would be OK.
However, regardless of the Mac notebook model, the hinge side must be up if the computer is running, vertical, and with a closed lid.
Offered for your consideration.
