After power loss, pc must wait for a couple of hours to boot

[SonicSkywalker]

So, as an example if there is a power outage or I unplug the power cable, then the power is back up or I replug the power cable, I have to wait for a couple of hours to boot it up.
What is most likely the cause of this?
Oh and also the BIOS resetted everytime it manages to boot up

 

[R_1]

the power supply.

 

[SonicSkywalker]

the power supply.

what happen to the power supply?

 

[R_1]

the power supply.

what happen to the power supply?

it sounds like a capacitor is not charging/discharging properly. the unit must build a charge to start the PSU and thus the system.

the BIOS resetting seems like the batter on the motherboard is dead, CR2032 lithium 3V for reference. if the power supply is not powering the motherboard when off the battery will have depleted itself over time.

what model power supply do you have? how old is it?