The computer with 4 pin does not turn on and the fans work without it, why ???

Question

Iron

I don’t know why, but after a hard day (for a computer), the computer stopped turning on, yesterday I watched all the degrees were normal, today I don’t start it.
I looked for the presence of swollen capacitors and did not find them. I
rearranged everything and took it out too.
It turned out that everything works without a 4 pin connector (except for the processor, of course),
and when I turn it back on, everything stops working.
Please help me figure out what's going on???

Answer 1

Here is the only correct algorithm in your case:
If you have a multimeter, and you know how to use it - disconnect all power from the motherboard, the multimeter for continuity (well, or for measuring resistance in the minimum range) - and check the + 12V processor power (4pin). If there is a short circuit (a few ohms of resistance) - the motherboard with the processor for repair. And the whole set is better - because. Perhaps the power supply has killed the board.
If there is no multimeter, we put a known-good PSU, and check. It didn’t help - again, the motherboard for repair (or better in the kit). It helped - the old PSU for repair (or for the trash, depending on what kind of PSU, some do not make sense to repair).
It's faster with a multimeter.

Answer 2

Because the cpu power line is for the cpu and the fans are from the common motherboard. The power supply is faulty: one line affects the other.

Answer 3

Test with another working power supply.
Perhaps the PSU does not pull the load - the processor, and without load it demonstrates minimal performance.