So the trick when troubleshooting graphic problems is to determine if it is the LCD or the video card.  The easiest way is plug in an external monitor to the notebook, if the external monitor shows the picture fine then the problem is with the LCD.   If the external monitor has the same problem then it is a problem with Windows / video drivers or with the video card itself. That test ofcourse requires having an external monitor, if you don't have one then the diagnostics can help.  The key to running diagnostics is to run the BIST test.  Run diagnostics by starting the system while holding down the FN key or by tapping the F12 key and choose diagnostics.  Allow the basic tests to start, after a moment you may notice a video test running, allow it to run and it will ask if it looked ok, you should choose no, this will start the BIST.  What happens is that once the BIST starts the video signal is actually generated by the LCD and not the video card.  So if you noticed the graphic problems while running normal diagnostics, you selected no, the graphics test didn't look good, the LCD would create its own signal, so if all of a sudden the image started looking good, with no problems that implies that the problem is with the video card,  while if the picture still looked bad and had the same problems the LCD is defective. So the questions that should be asked, are as follows: While running the video test it will ask if the display looked alright.  You chose no, the BIST started, did you still notice the vertical lines? You tested with an external monitor, did the vertical lines go away? If you answered yes to these three questions then the problem lies with the LCD.  If you answered no to the questions then the problem lies with the video card.
Hello, I'm trying to help a friend who has a DELL PP25L laptop she got it from her brother .It was purchased around 2011 with Vista if I remember correctly. I recently did a complete re-install of Windows8 and the laptop ran fine with it for a while. But now my friend is getting errors of horizontal colored line across the screen, and sometimes screen going dark, she has to restart frequently but the problems got worse and she is almost unable to use it. What can I do ? I did run the DELL diagnostic but that did not detect a problem. We checked if Windows 8 had the latest update and we have Defender anti-virus up to date. Can somebody help determining if this is a HW or SW problem ? Thank you .
DELL laptop PP25L screen problems