The manual even states it must be PS/2, mouse anyway, and keyboard must have the old win98 style on/off buttons also stated in the manual.
I use USB devices, and the only time I can resume a board via USB is by mouse and that mouse must be on a USB to PS/2 adapter.
However, there is a new BIOS option for USB wake (Can't remember what it is, maybe mouse), so you may want to check if that is enabled on your board.
To check that on the MAIN page of the BIOS press Control + F1, then go into the power settings and you will see the new Wake from USB something. Now that I type that out I think it is wake from USB, so please check that out. I will check for you myself as soon as I get a few posts replied to here.
*Edit*
Just checked, and the above is correct. It's a new hidden setting, Wake from USB Device S3, so please use the hotkey and ensure this is enabled. Not sure if that applies to mouse or keyboard or what?
And as with any USB Device, some may not be compatible, so if you can wake your other board with USB KB or Mouse, but not this board, try the other devices from the working PC on this trouble one.