Dell S2715H User Manual page 40

When the monitor does not support a particular resolution mode, you will see the
following message:
This means that the monitor cannot synchronize with the signal that it is receiving from
the computer. See Monitor Specifications for the Horizontal and Vertical frequency
ranges addressable by this monitor. Recommended mode is 1920 x 1080.
You will see the following message before the DDC/CI function is disabled:
When the monitor enters the Power Save mode, the following message appears:
Activate the computer and wake up the monitor to gain access to the OSD.
If you press any button other than the power button, one of the following messages will
appear depending on the selected input:
40 | Operating the Monitor