What laptop is this by the way? Try to include the Graphics Adaptor as well if you could. Failing that a model/build number for us to work with.
I have seen this many times before in the past and the reasons I have found have been:
- Loose or damaged SLI cable on a laptop
- Damaged GPU (As Saga Lout has kindly pointed out)
- The one I have seen the most; a loose or damaged cable that plugs into the screen from the GPU.
Good luck in solving this!