A processor needs a steady voltage at the instant a group of transistors switches. In a densely wired chip, the metal that supplies current competes for space with the wires that carry signals. Moving the supply network to the back of the silicon changes the route electricity takes to reach those transistors.
What difference could that make when an AI processor runs an inference? An Intel experiment on a fabricated processor core gives a measured frequency benefit. A separate study of an Arm core design shows how the choice of power rails changes the voltage lost along the way. Together they explain which parts of a chip can gain operating margin, why clock speed alone cannot predict response time, and what an engineer would have to measure to establish energy per inference. The comparison also helps interpret recent process results that combine backside power with changes to the transistors themselves.