HWPM stands for hardware power management and is a new power saving function that was introduced
with the Intel Broadwell processor generation. The option "HWPM Support" can be used to configure two
operating modes, which - depending on the respective utilization - assume control of the processor
frequency in a similar way to legacy power management, which is based on enhanced Intel SpeedStep
technology. In contrast to legacy power management, in which utilization evaluation and control of the P
-states is regulated by the operating system, i.e. in the software, these tasks are in the case of hardware
power management taken on in the hardware by the processor itself.
The setting "HWPM NATIVE MODE" provides the operating system with an interface, via which restrictions
and information regarding power management can be passed on, and which are then taken into account by
hardware power management for controlling. If on the other hand the setting "HWPM OOB MODE" is enabled, hardware power management then autonomously takes on the controlling of the processor frequency, i.e. completely independently of the operating system. In this case, the behavior can only be influenced by means of the BIOS option "Energy Performance". The BIOS options for legacy power management's "Enhanced SpeedStep" and "Turbo Mode" are no longer available in both "HWPM NATIVE MODE" and in "HWPM OOB MODE". In this case, the Turbo Mode is controlled by hardware power management. The standard setting for the option "HWPM Support" is "Disabled" and legacy power management is thus enabled via "Enhanced SpeedStep".
Comparative measurements have shown that legacy power management together with the current Windows
Server 2012 R2 operating system has minor energy efficiency advantages compared with hardware power
management. Nevertheless, hardware power management can be the better choice for operating systems,
which do not offer legacy power management support or offer inefficient legacy power management support.
- couldn't find any values on savings provided by this (or not)