FULL DELL ARTICLE: http://www.dell.com/support/article/us/en/04/sln128867/how-do-i-run-diagnostics-on-a-dell-monitor-?lang=en#Maintenance

Self-Test Feature Check (SFTC)

Dell monitors provide a self-test feature check (SFTC) that allows you to check whether your Dell monitor is functioning properly. If the Dell monitor and the PC are properly connected but the monitor screen remains dark or with a blank screen, self-test feature check (SFTC) allows you verify if the Dell monitor is functioning normally.

Run the monitor self-test feature check by performing the following steps:

  1. Turn off both the PC and Dell monitor.
  2. Unplug the video cable(s) from the back of the PC. To run a proper self-test feature check (SFTC), remove all digital and analog monitor cables from the PC. 
  3. Turn on the Dell monitor. A floating dialog box should appear on-screen (against a blank or black background), if the monitor cannot sense a video signal and is working correctly. If nothing appears on screen, chances are that the monitor may be at fault.Try to reset the monitor to factory settings using the On-Screen Display (OSD) menu. For more information on resetting a Dell monitor to factory settings, refer to the User Guide of the Dell monitor at Dell Manuals website. 
  4. Turn off the Dell monitor and reconnect the video cable(s). 
  5. Turn on both the PC and Dell monitor. If the monitor screen still remains blank or black, check the video card (GPU) and PC settings as the monitor is functioning normally.


Monitor Built-in Self Test (BIST)

Dell monitors are equipped with a built-in diagnostic tool that helps determine if the screen abnormality you are experiencing is an inherent problem with the Dell monitor or with the video card (GPU) and PC settings.

When you notice screen abnormalities like flickering, distortion, clarity issues, fuzzy or blurry image, horizontal or vertical lines, color fade etc, it is always a good practice to isolate the monitor by running the built-in self test (BIST).

To run the monitor built-in self test (BIST):

  1. Make sure that the monitor screen is clean (no dust particles on the surface of the screen).
  2. Unplug the video cable(s) from the back of the Dell monitor and the PC. The Dell monitor should now enter self-test mode.
  3. Press and hold Button 1 for 5 seconds. A gray screen should appear (Figure 4).
  4. Carefully inspect the screen for abnormalities.
  5. Press Button 1 on the front panel again. The color of the screen should now change to red.
  6. Inspect the screen for any abnormalities.
  7. Repeat Step 5 and Step 6 to inspect the screen in green, blue, black, white and text screens.
  8. The test is complete when the white screen appears.

Press Button 1 to exit the built-in self test diagnostics.