Question 5 year old PC shutdown and boot issue with fans running

[GreenHouseGas]

Motherboard:GA-990FXA-UD3 R5 (rev. 1.0)
CPU: AMD FX-8350
PSU: 550 watt themaltake gold (5 year warranty one)
GPU: GTX 950 MSI
RAM GSkill 16 GB DDR3
Window 10 recently updated to 20H1

Recently had this suddenly turn off issue and shutdown issue.

Sometimes when I manually shutting down using the window shutdown button, all the fans would stay running (CPU fan, GPU fan, PSU fan) the led indicator would show PC is on, but the screen is already off.

Sometimes when running normally the PC would suddenly shutdown.(sometime shutdown all the power and sometime shutdown with all the fan on.) And if try to turn back on again it would not boot but with all the fans on like previously described. But if I wait for like 20 min to turn on the PC would boot up again.

Note - when the sudden turn off happens it is like turn off in a blink of a second.

I am not sure what problem it is, so far tested the RAM no issue with RAM. Could this be PSU or motherboard? Or could it be window update related?

 

[lvt]

Sometimes when running normally the PC would suddenly shutdown.(sometime shutdown all the power and sometime shutdown with all the fan on.) And if try to turn back on again it would not boot but with all the fans on like previously described. But if I wait for like 20 min to turn on the PC would boot up again.

I've had this issue once with my Asus motherboard (775 socket), it seems like a capacitor or VRM related issue, you need to let it cool down then it will work again. I ended up replacing the motherboard.

 

[GreenHouseGas]

I've had this issue once with my Asus motherboard (775 socket), it seems like a capacitor or VRM related issue, you need to let it cool down then it will work again. I ended up replacing the motherboard.

Seems like it is the PSU. I switched in a new PSU, tried restarting 2 or 3 times and shutdown 2 or 3 times no bad symptoms like what I describe above occured. I guess I will use it for 2 or 3 days if nothing occurs, then it is the PSU for sure.

 

[lvt]

Seems like it is the PSU. I switched in a new PSU, tried restarting 2 or 3 times and shutdown 2 or 3 times no bad symptoms like what I describe above occured. I guess I will use it for 2 or 3 days if nothing occurs, then it is the PSU for sure.

You did it right, I replaced the motherboard because I have a PSU tester which shows no power issue.