I do not know anything that would be specific to the 802.1x problem, but maybe the cause is in the initial link up timing for the Ethernet.
There have been BIOS updates to some boards with 82579 network connections that might affect connectivity. Updating the BIOS might help.
If the computer has a management engine that uses the network connection for access, that might affect the initial connectivity. Make sure the management engine version and any associated drivers are the latest that Dell has for your computers.
If neither of the above ideas help, you could experiment with feature configurations that might affect the Ethernet link negotiation. For example, you could try disabling Energy Efficient Ethernet on the 82579 or try disabling PoE on the switch port. Either of these could affect the link negotiation.
I am curioius to hear back about anything that seems to fix the problem or make it happen less.
We'll try these. I did peek through the BIOS fixes/updates and didn't see anything specific for this issue, but it's definitely worth a shot at this point.
EEE is also a good thought... and we do have PoE switches, so these two things are something we should be able to do relatively easy/quickly. Sometimes it takes a day or two for our machines to fail, but I'll keep you posted on our progress.
I haven't worked with these devices in years, but I can answer your question about the BIOS. I was referring to the system BIOS. These devices are built in and the BIOS of the system can affect connectivity. I don't know anything specific about the 802.1x issue.
Not sure if ryantfsl is still around or if anyone else has experience with this issue and can chime in. Maybe one of the network people who monitor the forum will have an idea.