Question PC turns on but no display and NO motherboard led lights

[solxiz]

Hey there! I've been struggling with a hardware issue and i've made a deep search on the web but i had no luck at all.
I changed my components recently, and I bought hardware from a friend and i've been using the new rig for over a month: motherboard, psu, gpu, and cpu.
Note: GPU and PSU were used for mining.

The specs are
PSU: Seasonic Focus FX 850 gold
GPU: Asus tuf 3080ti
CPU: Ryzen 7 5800x3d
Motherboard: Asus Rog Strix B450-F Gaming II
Display: Zowie 240hz

This is how things went:
I had to test an AMD 570 gpu to make sure it functions in order to sell it, so I replaced my 3080ti for the 570. The PC booted normally to Windows and the GPU worked fine so I shut the system down and changed again to my 3080ti, but I couldn't get it to boot anymore.
Case fans, CPU fan and GPU turns on, but the USB ports and leds from the motherboard are dead. Also no beeps from mobo.

Things I've tried:
-Cleared CMOS by removing the mobo battery
-Flashed bios (the bios USB worked fine but ONLY when doing this)
-Tried another PSU
-Tried three different GPU
-Tried with only one RAM stick placed at every RAM port, and also tried another completely different RAM stick that I know for sure works. And also tried with no RAM connected at all
-Disconnected everything from the mobo except for the obvious things it needs to boot

By that point I gave up and contacted a professional that can help with my issue, but i needed the PC as fast as possible, so my friend (the one i bought the components from) gave me the exact same motherboard. Then, I connected everything and IT WORKED. The new motherboard leds turned on and I used the PC just fine that day. This was on last friday.
Saturday and sunday I wasn't home. I returned on Monday and when I started my PC, the same thing again. Everything starts except I have no led lights, not a single one at any time, no usb ports functioning, no beeps and no display of course.

So now it makes TWO motherboards damaged.
The only thing I have wrong in my PC case is my power button. I have to press it multiple times so I can turn on the PC. But i have been with that issue for the past five years without fixing it and i had no trouble with my old PC. And three differents experts told me that that wasn't the problem and that the issue could be the PSU

I will take ALL my components to an expert but he is busy this week so I need to keep trying things that could work and that are in my reach.

Any thoughts? Could've been the 570 that broke my PSU? or maybe the PSU was already broke and i had no clue (given the fact that it was used for mining)

 

[XxDarkMario20xX]

Maybe the GPU is at fault here and since you bought mined PSU and gpu that could be reason. PSu been on for mining so been stressed out to much and never ever should buy PSU that been mined could be faulty or break at any time taking parts with it Comment about power switch you can buy 3rd party one from amazon and use it to turn it on that way called a power button switch pc

 

[Lutfij]

Welcome to the forums, newcomer!

Note: GPU and PSU were used for mining.
That doesn't inspire much confidence on those parts. How old is the PSU listed in your specs list?

Tried another PSU
Make and model of the PSU?

 

[solxiz]

Welcome to the forums, newcomer!

Note: GPU and PSU were used for mining.
That doesn't inspire much confidence on those parts. How old is the PSU listed in your specs list?

Tried another PSU
Make and model of the PSU?

Hey there! thanks a lot i've been using this forums for years but never made an account until now
The PSU and GPU were used for mining for no more that 1 year, maybe less. But sadly my friend doesn't have the exact time info since he had more than 70 rigs for mining during the past year. And now i'm thinking i should ask him if he bought them new or already used.

The another PSU i tried is a Gigabyte P650B 80 plus bronze (used for only six months)