Dell U2913WM User Manual page 50

OSD Warning Messagess
When Dynamic Contrast Feature is enabled (in these modes: Game and Movie), the manual brightness adjustment is disabled.
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 2560 x 1080.
You will see the following message before the DDC/CI function is disabled.