Buy a UPS(uninterruptable power supply). It will recieve the 'power fluctuation' and store a small amount of energy in its battery. It will also regulate the varying voltage that is getting to your place. You plug the UPS into your wall outlet and plug the cpu into the UPS.
But you also need a new power supply in your computer. It should regulate the voltage and current on its own and has probably gone bad. That would be the immediate cause of your motherboard(s) burning out.
I have ups, spike box, good smps also that is important for a computer running properly but I don't know why for 2 years I had problem of motherboard burn out, and had to give to service 2 times this year and now engg have gave off saying my motherboard is dead and I have to buy new one. Even it was out of warranty now.
I have Intel motherboard. I live in 13 years old apartment where there is problem of power fluctuation and there is no earthing wire nearby. I cannot simply change my motherboard in a year or give in service daily without being used much. Please help me out of this problem what should I do?

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