It may be a small percentage of total power at full load but what about at idle? Modern CPUs try to optimize power usage by remaining idle as much as possible.

It may be a small percentage of total power at full load but what about at idle? Modern CPUs try to optimize power usage by remaining idle as much as possible. When idle, power usage is roughly in proportion to die area fraction. Since caches have been getting larger and larger this would represent a larger fraction of total power at idle.