the demon earth
Many years ago, in India, we had mail appliances fail every 2 months.
Yep, mobo burned, replacement was painful, because of customs, and it happened so many times, vs. many other sites where the same *never* happened once.
At one point, I asked the dudes where they plugged the double PSUs setup. Of course, to 2 different power sources like is best practices.
After asking them to plug both PSUs to the same power source, the issue never re-occurred.
Yep, the 2 earth from the 2 power source were very different and it repeatedly killed the mobos *every* single time.
In the same way, I had great flashes when working at one building, years ago, between my hand and the coffee machine, even after touching the other coffee machine 2 meters away. Yep, 2 connected buildings, and the earth was not connected properly, and have 100 V give or take voltage difference.
Earth is a bitch.