From SD
" I can't remember if there's something you have to do in the PC BIOS - any modern BIOS will support it, though."
Maybe the BIOS will need to be tweaked: my last m/c needed it set; this one didn't - worked from switch on. But it's easily found on the power management page - DEL on boot as usual & navigate.
From Keygrip
"Does the little green LED on my Asus (spit) motherboard stay lit when (if) my machine assumes it's winter." Nah - stays on all the time even during Double British Summer time. Which is why I respectfully disagree with SD:
"There should be zero power consumption for hibernation, as system state is written to disk, not VRAM."
Last bit of the sentence <true>, first bit <false>, as the PSU has to supply a teeny bit of amps to the board, to respond to a keyboard re-boot, not to mention KG's little green LED... and since it (the PSU) isn't designed to work most efficiently at low power there will be "a bit" of the old electric used in keeping the little green light lit.
That is my submission, me lord.