Agree on the sleep state stuff. idk who's fault it really is, but at least on the software front I mostly blame microsoft, because it's really their duty to deliver consistent, reliable power consumption on battery power.
The processors/chipsets seem to do what they're they're supposed to. However, it's far too easy for other parties to create a scenario that prevents the system from reaching deeper c-states.
Motherboards manufacturers produce boards that can't go below C3, despite showing up to C10 in the bios. The actual level of support won't ever be mentioned.
PCI devices, e.g. wifi cards, can prevent the system from reaching deeper C states entirely.
Putting devices into a PCI slot connected to the CPU lanes rather than the PCH can also prevent the system reaching the desired states. The CPU slot will frequently be the only choice.
Operating system defaults often prevent the system from reaching deeper c-states. Linux has been worse for this than Microsoft in my experience.
