BenQ XL2420T User Manual page 14

Turn on the monitor by pressing the power button
on the monitor.
Turn on the computer too, and follow the
instructions in Getting the most from your BenQ
monitor on page 21
software.
To extend the service life of the product, we recommend
that you use your computer's power management function.
When the monitor is powered on, to prevent overheating,
do not cover the monitor with the supplied protective cover
or obstruct the ventilation holes.
14 How to assemble your monitor hardware
to install the monitor