AFAIK, I believe the display's self-test is purely internal, not taking a signal from the GPU. So, I believe that any fault seen on that test indicates a problem with the display.
Hello I've searched on this condition, but haven't found what I think is a definitive answer. As of yesterday, I noticed that about the right 1/3rd of the screen on my trusty old E6440 is suddenly slightly darker than the rest. I'm attaching a screenshot, below. My laptop has the original FHD screen and is AMD/Intel.This condition persists when running Windows or Linux, so isn't a driver or GPU issue, AFAICT. I'd also note that in some circumstances the line is only visible (to me, who's colorblind) on windows or portions of the screen that are of a particular shade, generally fairly light but not bright white or darker colors (where I can't really see it). I think this is a totally unimportant observation, but thought I'd put it out there. The screenshot I chose has an off-white background, where you can see the change very clearly.The screen has always had some bleed at the bottom, but now I also see some very slight areas of darkness right at the bottom (looks like a couple of extremely low mountains on a flat horizon). One is directly below the vertical line that splits the lighter and darker parts of the screen, and the other is maybe midpoint between that and the right edge. If I press with a decent amount of pressure on the bottom of the screen just around where it changes, I can make the darker area get brighter again (return the screen to uniform brightness).My guess is this has to do with the LCD cable - either it's bad or needs reseating, maybe at the back of the screen. But could it be the screen itself? I don't think this model has a separate backlight or inverter. Something like an inverter may be build into the cable.Anyway, looking for any advice before I pull it apart.Thanks   [IMAGE]      
Latitude E6440 screen darker on right side