Sounds like a graphics card problem, or possibly the screen's connections to the MB. Might be worth connecting an external monitor if available and seeing if that suffers the same.
On one of my Dell laptops there are two video cards - the onboard Intel and a separate nVidia which tends to be used to drive external devices. So, the OP would need to know which outputs use the same video card - normally just a 15pin VGA, if available.
Might also be a heat issue SPECCY is good for monitoring temperatures on the motherboard, CPU and (in certain cases) Graphics card/processor.
M H C
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Edited by MHC (Thu 23-Jun-16 12:09:43)