Dell UltraSharp U2412M User Manual page 36

This m eans t hat t he m onit or cannot synchronize wit h t he signal t hat it is receiving from t he com put er. See Monit or Specificat ions for t he Horizont al and Vert ical frequency ranges addressable by t his m onit or. Recom m ended m ode is 1920 x 1200.
You will see t he following m essage before t he DDC/ CI funct ion is disabled:
When m onit or ent ers Power Save m ode, t he following m essage appears:
Act ivat e t he com put er and wake up t he m onit or t o gain access t o t he OSD.
I f you press any but t on ot her t han t he power but t on, one of t he following m essages will appear depending on t he select ed input :
VGA/ D VI - D / D P in pu t
I f eit her VGA or DVI - D or DP input is select ed and bot h VGA and DVI - D cables are not connect ed, a float ing dialog box as shown below appears:
or or