Trustworthy or dangerous?

Hi everybody, I know that it's a neverending fight, but still... How do I find out which PSU is best for my rig? I visited the PSU Discussion page, and the link there to find the PSU wattage by GPU. That is wrong. Why? Well, because... what if I have, say, RTX 4090 and some "dead" i5 12600K...

So, to get right into it: I have a custom built pc, originally from CyberPower but since modified. A couple months ago, the whole thing stopped working, and since I was going away for a while, I opted to let a computer repair store fix it for me. They installed a new motherboard, when I got home...