Your PSU is a consumer grade AeroCool with 80 Plus efficiency and narrow input voltage range. Never liked AeroCool.
Provide us details about your GPU type, count and connection scheme - type of risers, power cables configuration, PCI-E cables connection to GPUs.
A simple power outage, when voltage drops from ~230V to 0V in fractions of second should not fry your PSU, while an overvoltage/undervoltage might burn some details and the PSU starts failing under load.
First check all ports for molten contacts. Then visually inspect your risers. If everything looks normally, put back the parts, take a voltmeter and check +12V in idle and under load with 15 min intervals.