PC doesn’t recognise ethernet cable.

Pauliiuuss · November 18, 2018

To make it short and clear, most of the parts are brand new and used only for a couple of days.

Motherboard : Asrock ab350m-hdv

Processor: Ryzen 5 1600 stock cooler

Ram: Adata xpg 8gb 2400mhz

Gpu: -

Yesterday I turned off the PC and everything seemed fine. I woke up today and grabbed another gpu (gigabyte gtx 550ti) from a friend and thought it would be a good idea to install it because I had an old one and I was in need of something better until i buy a new one for myself. So out with the old one and in with the new and I remembered that i didn’t pull the power cable out. I pull it out, and them connect the pcie cable to gpu. I turn on my pc and the I notice there is no internet. I instantly realise that I could have shorted someting while putting the new gpu. But the problem is my router still detects a signal from computer when I plug the power cable in PSU. Which means that it still sends out power to LAN socket. And also the USBs that are on a same chip is working fine without ant problems. Could it still be that I’ve shorted my LAN port only without damaging usb ports on the same chip and how is router getting signal that it’s connected then.

P.S. Tried reinstalling drivers and pluging in different cables, even straight from the internet box and nothing changed. LEDs on LAN port also doesn’t work, because it sais it cannot detect any cable.

P.S.S. There is no visible physical damage on the motherboard.

mariushm · November 18, 2018

The lan socket isn't powered, there's no power there.

Inside the connector, there's a tiny transformer which isolates all pins in the ethernet jack from the computer, but that's it. The signal comes from (and incoming data is sent to) a network card chip which is circled in the picture below :

In rare cases it can happen for someone to accidentally break the chip or damage some components around it when inserting a video card into the pci-e slot. if a person is not careful the metal bracket can push down on components there, or can short circuit pins on the chip as the card is placed in position to be screwed to the case.

Visually inspect the ethernet jack and make sure the pins inside don't overlap one another (all should be parallel and sort of springy when touched) then make sure the onboard network card is enabled in bios - you pulled out the bios battery which may have reset the settings and therefore the onboard network may be disabled by default - if it doesn't work, I guess you're out of luck. It's really unlikely that the ethernet jack is faulty, it's higher chance you damaged something on the board. In that case, easiest solution is to just go in bios and disable the onboard network, then go and order a pci-e x1 network card, they're cheap, you can find some from 2$ and up (on ebay), and stores like newegg have some for around 10$.