I'll try to power down and test this for you by tomorrow AM - got some video transcodes going & don' wanna 'break' the files... Have a Logi G11 on a USB port - they're, well, problematic is probably kindest (PITA is more accurate!), so if it works on this thing, probably anything (short of a G15 - I hear they're even worse!) will work!
No, it does not support power up the system through USB device when system is in S4/S5 mode (hibernate/shut off). But it indeed work for S1/S3 (POS/Suspend).
Finally got around to a few power-down, BIOS, reboot cycles... Indeed, Fatbird is right: neither power on via keyboard nor mouse work with USB (at least, not with mine )
I have an Antec case that the button is hidden behind a door, which is locked to prevent kids from opening it. The power is controlled by a switch that is out of the reach of kids. Turning it on by keyboard is a desirable feature.
Ahhh - a reason! Just wanted to know it was not some dippy kid with an itch, before going into depth! (You would not believe some of the things here - spent way too much time with someone who was having trouble with USB power delivery, and had 'toasted' a port on his MOBO, only to finally discover he was trying to run a desk lamp off it!) Perhaps you might try the method I use for my CMOS reset: I take a couple of SPST miniature switches:
http://www.radioshack.com/product/ [...] Value=SPST wired in series, with most of the head sanded off, to make them harder to push (in the case of CMOS reset, I wanted to eliminate the possibility of 'accidental' resets, while avoiding opening the case and crawling around under my desk with a jumper in hand...); you see them here:
at the outer edge of the lower bay. Just drill a cople holes (and they don't have to be in or on the case, either...) and mount them... They have to be activated with the edges of a thumbnail because of the sanding job, which is easy to do intentionally, for an adult, but would likely prove difficult for a child. How old is the child? I think, after seeing you turn it on twice from the keyboard (assuming he/she can see/reach the keyboard), it will no longer be a secret! We tend to treat kids as, well, kids - but, if we could keep learning at the rate they do, all our lives, everyone would speak eight languages and know calculus! Makes them devilishly difficult to 'stay ahead of'!!