You need to go to the Advanced tab, and then to "APM." In APM, you want to set ErP Ready to DISABLED. Once you've done that, other options might appear (they do in the non-EVO), including "Restore AC Power Loss." Set that option to "Power On" or "Last State" if you want it to go back on if it was on, or stay off if it was off.
Something about this should be in the motherboard manual in the BIOS section. Keywords are APM and ErP.