|You can often set bios settings such that the computer will auto start up after losing AC power - having the power to the case off and then switching it on will start up the computer. Some rooms such as a living or dining room may already have a wall switch that enables / disables the power to a wall duplex or one of the two plug-ins in it. |
You could run an extra pair of wires to the two pins for the power switch on the mboard and use a "normally open" switch at the other end - as in, momentary contact, it's on only when you press it - that will switch it on, or off, the same way the power switch on the case does. All ATX computer cases have that type of Power switch, and all AT and ATX cases have that type of Reset switch, if it has one.