The BIOS setting is for APM, a subsystem your current
OS is not using. My APM section is all switched off.
When the OS is booted, go to Device Manager, find the HID
device that you want to be starting the computer, do Properties,
and one of the tabs on there says
"Allow this device to wake the Computer"
That's the tick box you want to enable. AFAIK.
The motherboard will be using +5VSB to run the USB
ports, and that's the power source that makes waking
possible. These motherboards don't have the old PWR header
plug, to select between +5V (no wake) and +5VSB (wake).
They're permanently powered with the +5VSB option
for waking.
You will also want to check the Device Manager mouse
settings. I have one mouse, which when "sleeping", does not
turn on the LED under any circumstances. It's only wake
input is mouse click. You need to enable that mouse
in the Device Manager, then a mouse click works. For
my newer Microsoft mouse, the blue LED in that flashes
for as long as it has +5VSB, and both mouse movement
and button clicks work. I keep that one turned off
in the Device Manager, so bumping it doesn't
result in a false positive.
I think my keyboard is on the combo PS/2 and waking
there works off any key.
There were motherboards, where the SuperI/O chip had
a "filter" on the PS/2 keyboard port. And in the BIOS,
you could set detection to four different keyboard
key press sequences. The P9X79, I don't see an option for
that, and as it's in the APM section, there probably isn't
a reason for the OS to look there. Use Device Manager
instead and see what is there.
Paul