Well, it also depends on the degree of integration, the drivers, and how the operating system running on the kernel works. There are a lot of very economical Linux variants; think access points, printers, routers, and smartphones (Android has a Linux kernel).

General x86 desktops that don’t have drivers are ideal because some network cards, USB controllers or GPUs aren’t supported by the manufacturer (many WLAN chips have a small built-in OS and ARM SOC on board, if you can’t figure that out: go to sleep, and keep your power consumption reasonable).

This will improve very quickly, especially as the firmware/hardware/OS stack improves. Consider Windows Modern Standby, for example. A feature that was developed because BIOS integrators and motherboard builders simply couldn’t create clean S1/S3 states, and Intel then managed to screw up the C states in their microcode.

Devices like the Steam Kit where the SOC, OS, and firmware are coordinated have much less issues with this, which is why you see “fast resume from hibernation” issues. It’s kind of the same as where a Windows XBox can hibernate/save and fast resume the game.

This is actually the big challenge for Linux. If you look at nVidia Optimus (basically where the nVidia card can, if necessary, render certain applications/tools, send the result to the IGP’s frame buffer, and then display that via the internal LCD, but it can also be a 100% discount), which is something that is used in practically every nVidia/Intel/AMD laptop that also has an IGP. For a long time, due to the crazy nVidia drivers (nVidia + Linux were not friends, as evidenced by Torvalds’ middle finger moment), the nVidia GPU couldn’t really work under Linux. And then it kept consuming power. And with some bad luck, not even at slower clock/lower volts. For fun, on an nVidia system, just type “nvidia-smi” into the command line. Even at idle you’ll see that this is often an extra 10 watts. And that’s not because Linux is bad, quite the opposite. This is because Linux (due to the manufacturers’ complete unwillingness) can’t do the trick. Hobbyists can often recreate this, it works, and finds its way into the kernel, or the manufacturers themselves get involved (think of the Steam group, or what AMD does in general).