4540s hardware manager does not show any ethernet card

[JCH2015]

The WIFI is there and works, but there is no device shown in the Hardware Manager for any ehternet card. I believe it should be a Realtek PCIe card.

In short, I want to make a wired network connection to my router. This computer has doen it in the past.

[Paul_Tikkanen]

Hi:

Your notebook has a LAN/WLAN switching setting, and a LAN power save setting in the BIOS.

The default for both of these settings is enabled.

When an ethernet cable is not connected to the PC with these settings enabled, the ethernet adapter is turned off to save battery power and does not show up in the device manager.

Once you connect an ethernet cable, the PC detects that and turns on the Realtek ethernet adapter and turns off the wireless card.

If you always want to see the ethernet adapter in the device manager, go into the BIOS and disable the LAN Power Save setting.

If you don't want the wireless card or ethernet adapter to turn off when one or the other is on line, then disable the LAN/WLAN switching setting.

[JCH2015]

Paul,

Thanks for you thoughts on this issue. In the BIOS I see an item "Embedded LAN Contoller". It was checked so I unchecked it.

The LAN/WLAN Switching was not checked, and I left it that way.

So... now I would expect to see the Realtek Controller in the device manager, correct?

I still do not see the Realtek device.

Here are some additional facts:

This device had been there in Device Manager before AND I did not change anything in the BIOS.

This device had worked in the past AND I made no changed to either the BIOS or the Device Manager.

I have done a scan for hardware changes and the Realtek does not seem to be discoverable.

I connect the Ethernet cable to another identical laptop and it works fine.

I changed the cable and there is not change.

Given the fact that this computer had regularly connected to the network using wires, why would I cosider the status of the BIOS settings?

What other likely issues could be causing the Realtek controller to not appear in the Device Manager?

[Paul_Tikkanen]

You're very welcome.

The embedded LAN controller is the Realtek ethernet device.

If you unchecked it, I assume now you have disabled it.

Most likely the Realtek ethernet chip on the motherboard had died on you if it had been working in the past, and plugging an ethernet cable into the port does nothing.

It happens.

[JCH2015]

Paul, Is the Realtek chip replacable? I have done a search for replacing the chip and find nothing. Does this mean I must replace the motherboard? Are there such things as an outboard network card that can be use in its place?

[Paul_Tikkanen]

Hi:

Unfortunately, the entire motherboard would have to be replaced in order to get the O/B ethernet to work again.

I think the easiest thing to do in your situation would be to purchase an external USB to RJ-45 10/100/1000 gigabit ethernet adapter, and that should solve the problem cheaply and easily.

[JCH2015]

Paul,

I value your help on this issue. And after extensive reading of many help forums on similar issues, I wonder if there is a definitive test to know that the Ethernet chip has failed, or do we simply infer that this is the case. Does the absence of this device appearing in the Device Manager absolutely tell us anything at all? I am looking for a bona fide test for the failed chip.

I saw various replies to issues like this that mentioned that the chip may simply be asleep and people were asking how to wake it up. (Apparently, this is not an easy task.) If this is a possibility, how do I test or know if the chip is not really asleep? So many forum answers that I have been reading fail to ever mention tests that can be done to narrow down a diagnosis of this issue, or any issue. Do the computer designers and manufacturers do a lot of guessing rather than true diagnosis?

Only a few forum answers arrive at the conclusion that the chip may have actually failed but they do not describe a true test for this condition.

[Paul_Tikkanen · Accepted solution]

You're very welcome.

I am not a PC repair tech by trade or training, so I do not know of any way to test the ethernet chip.

And yes you are correct...there is a condition where the Realtek ethernet chip has a condition known as deep sleep mode. 

But that normally only occurs when you are first installing the operating system, and fail to install the Intel chipset driver first and restarting the PC, before installing the Realtek ethernet controller driver. 

You install the Realtek driver, and the driver package reports that the Realtek ethernet controller is in deep sleep mode, and the driver cannot install if the chipset driver was not installed first.

I can tell you how to confirm or rule that out as a possibility.

1. Install the latest chipset driver directly from Intel and restart the PC. 

The 2nd driver on the left side of the page is the auto install file.

https://downloadcenter.intel.com/download/20775/Intel-Chipset-Device-Software-INF-Update-Utility-?pr...

2. Install the latest ethernet driver directly from Realtek and restart the PC.  You want the 4th file (W7) on the list.

Download, unzip and run the setup application.

http://www.realtek.com.tw/downloads/downloadsView.aspx?Langid=1&PNid=13&PFid=5&Level=5&Conn=4&DownTy...

If the Realtek ethernet controller shows up, then somehow the drivers got messed up, and you're good to go.

If it doesn't show up and/or the driver reports it is in deep sleep mode, then you can pretty much assume the chip is dead.

The driver can't tell which is which (really dead or in deep sleep), and can only report that condition if it can't find the ethernet controller hardware.