Why does the PC turn on for a moment and then turn off when plugged in?

Question

Iron

I assembled a PC, when the plug is plugged into the outlet, it tries to turn on, but immediately turns off after a second. Then you need to press the power button and it works as expected.
In Bios, I found only one item related to similar behavior, but I saved it anyway, and saved it differently, anyway, it tends to turn on itself. And the main thing is that it does not turn on! Just tries and stops.
Bios UEFI asrock

Answer 1

I assembled a PC, when the plug is plugged into the outlet, it tries to turn on, but immediately turns off after a second. Then you need to press the power button and it works as expected.

This is how some PSUs and some motherboards work. This is especially common just in the presence of UEFI. A kind of test start so that the cold start works remotely, for example. I can’t immediately think of how else to explain, but actually I don’t fully know the subtleties :).

Answer 2

At our work, this happens on several hundred PCs. At the same time, this does not affect the stability of the work.