Dell P2720DCc User Manual page 52

This means that the monitor cannot synchronize with the signal that it is receiving
from the computer. See
frequency ranges addressable by this monitor. Recommended mode is 2560 x
1440.
Before the DDC/CI function is disabled, the following message is displayed:
When the monitor enters the Standby Mode, the following message appears:
If you press any button other than the power button, the following messages will
appear depending on the selected input:
Dell P2418HZ
52 │ Operating your monitor
Dell 27 Monitor
The current input timing is not supported by the monitor display.
Please change your input timing to
monitor listed timing as per the monitor speci cations.
Monitor specifications
Dell 27 Monitor
The function of adjusting display setting using PC application will be
disabled.
Do you wish to disable DDC/CI function?
Yes
Dell P2418HZ
Dell 27 Monitor
Going into Standby mode...
Dell 27 Monitor
?
No HDMI signal from your device.
Press any key on the keyboard or move the mouse to wake it up.
If there is no display, press the monitor button again to select
the correct input source.
2560x1440, 60Hz or any other
for the Horizontal and Vertical
No
P2720DC
P2720DC
P2720DC