F2bnp wrote:

Also, it's not the PSU, I've tried different ones, just in case, and the result was exactly the same.

OK, so create a matrix of tested X with Y and Z and test combinations until the dead parts have been identified.

With old parts, multiple failures are commonplace, making troubleshooting more difficult, but the worst situation of all is when absolutely no combination of the compatible parts that you have on hand works and you have to get more just to figure it out.