Dark silicon
The phenomenon that you can no longer power all the transistors on a modern chip at once — it would draw too much power and get too hot. An ever-growing fraction of the chip must be "dark" (turned off) at any given moment. A central consequence of Dennard scaling ending.
Background: previously (Dennard scaling) the power per transistor dropped as they shrank, so you could power more transistors on the same chip without the power exploding. That stopped holding around 2005 — transistors keep shrinking (Moore's law) but the power per transistor no longer drops in step. Result: you fit MORE transistors than you have POWER BUDGET to drive at once → some must always be turned off (dark). Consequences for design: instead of making one big general core faster, you spend the transistors on specialized accelerators (for AI, video, crypto) that only light up when needed and are far more efficient for their task. It explains today's heterogeneous chips full of fixed-function blocks. A fundamental driver in modern chip architecture. Related to heterogeneous cores and thermal design power.