That’s what I was taught back in school, the end of Dennard scaling pushed the industry to multi-core, as well as huge temporary power limits to race to the finish as needed for better average efficiency. IIRC the current power density for modern chips is near that of a nuclear reactor.

Edit: yep, this was the source of the claim, slide 4: https://www.glsvlsi.org/archive/glsvlsi10/pant-GLSVLSI-talk.... A 3090 will spike to 500W+ which ends up being ~80W/cm2