So it looks as if Afterburner is the issue since GPU-Z doesn't show the sensor jumping up and down. The reason I had you check with GPU-Z was to verify it wasn't a faulty sensor.
At this point I'm not sure what to tell you. I know that there is a level of support for mobile nVidia GPU's built into Afterburner, but I don't know how inclusive that support is.
If you really need an answer, I know the developer spends a lot of time over at the forms at Guru3D. He has a support thread there, you could query him and post the image. Just be careful how you word your question, he can be sort of touchy.