In the long run, stability will always win (I can't use smart plugs or "resetters" for this as I have frequent blackouts in my country and smart plugs or "resetters" DOES NOT turn back on after a blackout, they need a manual input), if you know a solution for this, please let me know.
I also highly advised using UPS when you turn this option on. As the Voltage is higher than usual after power outage. Could damage your components.
Your Power Supply (PSU) For your motherboard/GPU's doesnt care how high or low your incoming power to your house is as long as its within a rather large window. The PSU is a regulated power supply. It will keep DC at 12vdc going to your GPU very close to 12vdc even if your incoming house power is at 240vac, 218vac and even up around 255vac. The owners manual will tell you what the exact spec for your particular PSU is but its a wide window. The PSU will shut itself down if the incoming is too low or high outside of its design specs. UPS is not needed but nice to prevent bumps to the motherboard but useless in the sense that your GPU's arent on a backup so they could hangup, freeze or just totally throw up once power is restored. (You gonna put your motherboard on its own dedicated PSU?) Otherwise the GPU's will be drawing power from the PSU (Ultimately the UPS) when the power goes out and it aint gonna last long.