Deep Power Down state (DPD)

Deep Power Down state (DPD) is the lowest possible power state. In this mode the processor flushes and disables L2 cache, saves the state of each core into on-die SRAM memory, and then lowers core voltage close to 0 Volt. Typical Thermal Design Power of dual-core mobile CPUs in this state is 0.3 Watt.

The process of waking up the CPU from DPD mode is initiated by a chipset. The chipset signals VRM to increase core voltage, then it turns on CPU's internal clock and wakes up the CPU. The CPU in its turn resets internal state, restores previously stored state from on-die SRAM, and enables L2 cache.

Deep Power Down mode was first introduced in Intel Penryn core.