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Intermittent onboard LAN issue - cable not connected error

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September 27, 2012 7:41:02 PM

I have a new build with a really strange problem.

At home where I built and tested, everything works fine, no issues from beginning to end.

I deliver the PC to its new owner (family member, luckily) and the onboard LAN won't recognize the cable. A few minutes later, it refreshes and discovers the cable, everything seems fine. I completed a few last minute personalization items and needed a restart. Upon restart, no cable detected, and it remained that way, undetected. After swapping and testing every cable I had with a laptop, all cable were confirmed working, as was the router and broadband connection.

After hours of reinstalling drivers and updating firmwares, wasting time on the phone with ASUS tier 1 support, etc, I decided to RMA the board at the request of ASUS. I get the board back a week later, reinstall again, test it at my home, use different cables, restart numerous times, works perfect.

I then bring the PC back to its new owner, promising a fix, and of course...same damned problem. I told him his house must be built on an old cemetery or something, but he wasn't buying it :) 

The router is a linksys e2500, firmware is up to date, wireless and other LAN devices function with 100% connectivity. All ports tested, confirmed working on other hardware.

Motherboard is an ASUS P8Z68-V/gen3. All of the drivers (chipset, LAN, USB, etc) are current.

I'm stumped...why does it function perfectly in my home, but not his? The two variants, router and modem, seem to function just fine.

What would cause the connection to fail on restart, but eventually, with no user intervention, connect and stay connected until another restart?

I'm going to install a NIC card in the next few days and see if it's simply the onboard. At that point I'll be furious with ASUS, but I'll at least know the source of the issue. But that still wouldn't explain why it functions at my home...

Any help, is of course, most appreciated.




September 27, 2012 7:51:20 PM

Sounds like a poltergeist.
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September 27, 2012 9:08:53 PM

If I were you I would bring your own router to the scene of the crime and see if it works when you substitute it. If so, then his router is to blame. I would start with resetting his router to default. I've had similar issues with the same message you are receiving, it was link speed negotiation with the router. Maybe you could try forcing the new PC to run at 10 or 100 Mb mode, instead of the default Auto or 1000 Mb mode.
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September 27, 2012 9:37:14 PM

Something else to bear in mind, it could be a patch cable problem at his home. My own setup at home is fully gigabit (other than internet router) and I periodically come across bad cables when I move my rigs around. Initially it presents itself as a broken cable until it can negotiate a speed it's happy with, normally 100Mb/s.

I would suggest checking "Task Manager" under the Networking tab to see what link speed he is actually getting.
Check the route of his cabling in case it's getting interference from the mains electrics.
Try your own patch cable on his kit in his home as well.
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September 28, 2012 12:36:56 AM

Thanks guys, it eventually did pick up the cable again. I jumped into his box with RD and sure enough the speed was only 10Mb, and should be a 100Mb connection. I had him swap out the patch cable between his router and modem, and now we've lost the connection to the pc again...

Seems we have narrowed the problem down to speed negotiation, assuming that the previously mentioned cable is not the issue, what are the other possibilities?

Once it's back online I can again RD in and check any onboard nic settings, but since it worked on my gig router, I'm assuming it's not the new box. Which leaves the router...I have remote access to that as well, and after poking around did not see any settings to change connection speed.

Getting closer to a solution though, so thanks guys!
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September 28, 2012 2:00:34 AM

make sure you have the newest network drivers for the mb. the newest drivers are on intel web page. make sure on the mb install cd you did not install Network iControl V1.03.09 for Windows Win7 32bit & Win7 64bit & Win8 32bit & Win8 64bit.
there a big bug in it that is causes the network speed to slow way down...know issue on the rog forum. the last could be a firmware or chipset issue with the onboard intel and the router.
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September 28, 2012 10:16:44 PM

I installed the intel proset drivers instead of the ASUS driver, more of the same.

I have narrowed the issue down at least. Seems the intel 82579v is a relative POS and many have issues. When connected to a 10/100 router, the nic will not connect at 100mb/sec, only at 10.

I'll prob have to install a nic card and call it a day.
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September 29, 2012 3:28:48 AM

Have you tried swapping cables to see if the cables are the problem?
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September 29, 2012 3:52:50 AM

Yeah, I've swapped about a dozen cables in and out over the few weeks I've been fighting this board.
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September 29, 2012 4:35:34 AM

Strange issue....if it's a new board you could try RMAing it.
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September 29, 2012 3:19:36 PM

I appreciate the help, but did you read the OP?
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September 29, 2012 6:49:07 PM

I did, have you tried forcing the duplex/speed settings? Sometimes NICs don't work well with other hardware (Cisco is known for this) and auto-negotiation fails to the lowest speed. Did installing a different nic card help?
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September 29, 2012 7:04:04 PM

Forcing the duplex setting to 10M is the only thing that works, which is probably fine for his needs, but it would be nice if it would run at 100 as it should. Trying to force 100Mb kills the connection and causes the "cable not plugged in" error, along with other system wide errors. This issue is widely reported on a number of boards that have the intel 82579 LAN.

The nic card worked fine, so the error is definitely narrowed down to a bad LAN/driver/router combo that will most likely not be fixed.
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September 29, 2012 11:44:13 PM

Interesting. How long is the cable run to the router out of curiosity?
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September 30, 2012 1:19:17 AM

what will happend if you install the lan driver from asus and try to see if the network off the owner is been detect by the internal lan card als o if you use win 7 try to create a new network connection with the owner network
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June 10, 2013 4:08:19 AM

PlowKing said:
Forcing the duplex setting to 10M is the only thing that works, which is probably fine for his needs, but it would be nice if it would run at 100 as it should. Trying to force 100Mb kills the connection and causes the "cable not plugged in" error, along with other system wide errors. This issue is widely reported on a number of boards that have the intel 82579 LAN.

The nic card worked fine, so the error is definitely narrowed down to a bad LAN/driver/router combo that will most likely not be fixed.


First of all thanks to you. Your experimentation paved the way for me to solve my connectivity problem. I had this problem :-

"I have Asus P8B75-M LX motherboard purchased 6 months ago. I have a little problem here. When I have connected my LAN cable to on-board LAN port then Window takes 10 min. to identify network after started up. Until it identifies, it keep saying "Network Cable is Unplugged". During this, in modem the LED for the LAN connectivity becomes ON for one second and OFF for one second. After 10 min. Window shows my LAN network is working and with this the LED on modem becomes normal.

On the other hand if I connect a PCI LAN card and use it instead of on-board LAN port I don't face any delay in connectivity, internet is active as soon as windows boots up completely. And LED on modem remains normal, like it fluctuate rapidly when I use internet and remains stable when I don't.

I don't understand why it does work fine with PCI LAN card but not with on-board LAN port. My specs :-

Mobo= P8B75-M LX

Processor= Intel i3 3220

Windows 8 Pro 64 bit"

Solution was :- In advanced settings of network adapter, for "Speed and Duplex" I set "10 Mbps Full Duplex". Now it is working fine.
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June 10, 2013 4:57:51 PM

Glad I could help!
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August 17, 2013 3:01:29 AM

Hey guys, have you found another solution instead of switching the setting to 10M?

I've got the same problem described by Shekhar5 but couldn't solve my problem by changing the Speed and Duplex settings.

Tried different drivers and even different SO (Win 7 and Win 8) but as soon as I get the cable connected to my router after installing the driver, my router goes crazy and keeps rebooting the connection (I've got 2 other computers on this router without a problem, but after connecting the new computer all 3 loses connectivity)

btw, I'm running a M5A78L-M LX/BR

Thanks in advance!
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!