Question VGA LED on MOBO and no display.

Feb 16, 2022
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Specs:
MOBO: AORUS ELITE V2 B450
PSU: Corsair CX600m
GPU: Radeon RX580
CPU: RYZEN 5 5600X

Hello!
So yesterday my pc turned off on its own, after that i tried to turn him on but unluckily it didnt. So the first thing i saw there is a VGA LED which is constantly red. I tried 2 others VGA so on first GTX 1050Ti i got screen but it was saying i have to connect PCI-E to power supply. On second gtx 650 it didnt showed anything like on RX580. So i tried to apply my PSU to other PC and it didnt worked too. I am not sure if its possible that if PSU is damaged it can turn on everything? I mean when im turning on my PC fans are spining and computer is working. I tried to exchange RAM and it didnt helped too. I tried with replacing HDD's and SSD's and it was the same thing.
What might be the reason? Mobo is like 3 months old but PSU is old af.
Thanks for every response! (Sorry for my bad english, i hope you understand everything)