Are you sure it is not a hardware issue, please? Could be the videocard is starting to fail, or already gone (damaged). As your computer is a laptop, the motherboard might be failing too.
Please note this photo looks very much like a hardware issue with your card, or your Dell mobile workstation motherboard.
What is your Windows OS? Such as WinXP, Vista, 7, 8/8.1, 10/etc.
Can you check if FurMark works? (Carefully however, NOT to overheat the card or your CPU/motherboard! If you see temps rising too much, stop the FurMark test immediately.)
Link:
http://www.ozone3d.net/benchmarks/fur/
Also, do some basic 3D tests - do 3DMark, Unigine Heaven, Unigine Valley - do you see anything unusual? Such as the screen you sent photo of, or any other glitches/artifacts - wrong/funny colors, lines where there should not be any, blinking pixels or areas?
You can download these here:
https://www.3dmark.com/
https://benchmark.unigine.com/heaven
https://benchmark.unigine.com/valley
Also, if you try an older GPU-Z version, such as 1.16.0, does the same thing happen, OR does it work fine?
You can download older GPU-Z versions here:
https://www.techpowerup.com/download/techpowerup-gpu-z/ (click
Show more versions link)
Also, please check if other similar apps work or fail:
http://www.ozone3d.net/gpu_caps_viewer/
http://www.ozone3d.net/gpushark/