Processor power issue?

Question

Computers

The computer does not show signs of life if you turn on the power to the processor (8 pin), but if you turn it off, the computer starts to turn on (fans spin, etc.), but the picture does not display on the screen.
PS: the power supply is working, 650 watts, enough for the eyes, because. costs i3 8100 and gtx 660

Answer 1

There is a chance that you have confused the processor power wires with the video card power wires. And there on the connectors the polarity is opposite. Those. the power supply will sense a short circuit along the + 12V line and simply will not start. Exactly matches your symptoms.
As far as I remember, this way you can mix up the 4-pin CPU and PCI connectors (they are inserted), as for the 8-pin, I'm not sure if it can be inserted incorrectly, but I recommend checking.

Answer 2

Get/borrow a multimeter and check.
The correctness of the power supply is checked with a multimeter.