Asus UX31LA - Manual (Page 17)

Notebook PC E-Manual 1
Power (DC) input port
Insert the bundled power adapter into this port to charge the
battery pack and supply power to your Notebook PC.
WARNING! The adapter may become warm to hot while in use.
Ensure not to cover the adapter and keep it away from your body
while it is connected to a power source.
IMPORTANT! Use only the bundled power adapter to charge the
battery pack and supply power to your Notebook PC.