I have no idea of the PC market in russia, but this seems like an okay price. Are you able to find out the motherboard? (you can check in system information) I suspect you need to replace to PSU and need to find if the motherboard uses standard power connectors.
Who sold you this and for how much. Have a feeling you massively overpaid. Anyway, I have never heard of "KING PRICE" and this is almost definitely the issue. Can you upload a photo of the label on the power supply?
So I just got a new PSU and ram now what's happening is the system is not bootlooping but still no display, but after about a minute the fans turn off and turn on very quickly. I want to pull my hair out this is so frustrating it makes zero sense
Was using a r7 450 and switched to an Rx 470, having same issue, only now it will never display anything... thought it was the CPU, a new CPU is coming today for me but since someone has almost the exact same issue as me maybe not?