How can a network cable (RJ45) affect the computer's power on?

Question

Iron

The stationary computer stopped turning on, it looks like this: I press the power button, the power indicator lights up, you can hear the fans start spinning and then everything turns off, after about half a second.
Using the method of scientific poke, I found out that the network cable (РЁ45) is to blame, if you pull it out of the socket and turn on the computer, it starts up in normal mode. Then I plug the cable into the connector, and everything works fine.
Perhaps the router is to blame, but there is no other handy, I can’t check (there is no such problem with the laptop). Tried resetting the BIOS, didn't help.
What's the attack? Network card kirdyk?

Answer 1

It was similar for a long time: I bought unsuccessful motherboards for work. Over time, about 4 out of 10 began to behave like this. Discrete setevukh removed the problem.

Answer 2

grounding you need to check because there is a short between the router and the PC

Answer 3

Maybe he is trying to boot over the network ... Try turning this feature off.

Answer 4

Try updating the BIOS first. It happens. For example, now when you turn off desktops, network cards often do not turn off, but go into 10 Mbit / s mode :) And then it may not go back ... The second thing to try is to change the power outlet of the router. If the router is powered from different phases with the computer, then reduce (if possible) to one phase. You can also try turning the desktop power plug 180 degrees. Well, RJ-45 itself can be changed to another. One of the three should help.