So with the PC plugged into AC power, and the PSU switch on, but the PC not turned on via the power button, you don't see any LEDs on next to the network input? If not, the port seems to be off or in a power savings mode. If I turn on the PSU after I've worked on the PC (removed AC power), I always see the activity LED flashing. But I don't use the same board, etc, that you do.
Have you checked the Properties of the network device in Device Manager? Specifically the Power or Power Management tab? WOL may not be enabled, among other power features, you did not mention checking those things.