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You still need to physically hit the reset switch.
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No need to *physically* hit the switch - you can do the same with a relay or transistor.
Or just power-cycle the PC - most BIOS can be set to automatically boot when powered up. It is probably easier to use an off-the-shelf software controlled mains switch connected to an arduino or similar than to connect a wire to the reset line of a PC. Also has the advantage of being hardware independent.