If that cap didn't spreading the heat as well, what you'd be seeing on the thermal camera would be something that glows around 60C-70C (because clearly, the cam

If that cap didn't spreading the heat as well, what you'd be seeing on the thermal camera would be something that glows around 60C-70C (because clearly, the camera's software can more or less resolve the room temperature reflection from 60C thermal radiation), and the color would be more or less uniform in the region above the CPU. There wouldn't be such a strong observed temperature gradient. Which is the evidence you're looking for.