Dell S2409WFP User Manual page 22

or
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 address
monitor. The recommended mode is 1920 X 1080.
When monitor enters Power Save mode, the following message appears :
or
Activate the computer and wake up the monitor to gain access to the OSD
If you push any button other than the power button one of the following messages will appear depending on the selected input:
VGA/DVI-D/HDMI input
or
If either VGA, DVI-D, or HDMI input is selected and all VGA, DVI-D, and HDMI cables are not connected, a floating dialog box as shown below appears.
or or