Dell UltraSharp 27 User Manual page 67

If either DP or HDMI input is selected and the corresponding cable is not connected, a
floating dialog box as shown below appears.
See Troubleshooting
No DP Cable
The display will go into Standby Mode in 4 minutes.
www.dell.com/U2724D
No HDMI Cable
The display will go into Standby Mode in 4 minutes.
www.dell.com/U2724D
for more information.
or
Operating the monitor | 67