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Dell Optiplex 755 with the Intel 82566 NIC constantly disconnects and reconnects to network.


We have placed 90 Optiplex 755 with the Intel 82566 NIC cards into three labs. These machines have Windows 7 Pro. These labs have Cisco 3550 switches for the network. Immediately after installing these systems we found that the computers kept connecting and disconnecting from the network. We have updated the firmware on the switch, and installed the latest driver on these machines. The problem continues. Dell has offered no support or help. The answer they gave me was, reinstall the OS, or the motherboard needs to be replaced. Odd that 90 out of 270 we ordered all need knew motherboards. We know it is a fairly common problem with this series of NIC's but have not located a solid fix for the problem. Also, as an FYI, we never had this issue with the systems in the lab previous to installing these computers.

Any assistance would be greatly appreciated!


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Have you tried using some older versions of the drivers? Some people have had luck using older versions that are available from the OEM or even rolling back to the Windows verion of the driver. My first thought was you might be able to find the drivers from Dell, but I only see Windows XP and Vista for your model at

According to the version information at, support for Windows 7 SP1 was added starting with version 15.8.1, so you probably would not want to go to an older version than that one.

Try the drivers at The drivers from this page are the version 16.5 package. You can ignore the description on this download. The packages do include Windows 7 drivers for the Intel(R) 82566 Gigabit Network Connections.

A slighlty earlier version, v16.2, of these drivers is at

Let me know if one of the older drivers solves the connection issues.

Mark H

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