Embodiments of systems, apparatuses, and methods for energy efficiency and energy conservation including enabling autonomous hardware-based deep power down of devices are described. In one embodiment, a system includes a device, a static memory, and a power control unit coupled with the device and the static memory. The system further includes a deep power down logic of the power control unit to monitor a status of the device, and to transfer the device to a deep power down state when the device is idle. In the system, the device consumes less power when in the deep power down state than in the idle state.