I have an Asus P8Z77-V mother board with the stated NIC. The latest drivers are installed: Intel Pro Set Version 22.214.171.124, Driver Version 126.96.36.199. I also have the latest BIOS.
I must force my NIC to 10 Mb/s (half or full duplex works) in order for it to recongnize any connection at all. Auto-negotiate and 1 Gb/s yield no connection at all, and the 100 Mb/s setting yeilds a cycle of connects and disconnects and an unresponsive system. (Sometimes my Display Adapter driver drops out durring this, too.) A connection with a D-Link router seemed to work fine, but a connection to an old Linksys router or to my apartment's ethernet jack (managed by Korcett/SuddenLink) yields the stated problem. My NIC from my previous motherboard works fine, and I have tried multiple Cat 5 cables and recently a Cat 5e cable with the same result.
Sorry to hear you are getting stuck with only a 10 Mbps connection. As to why, I can only speculate.You already have the latest driver, so there is no upgrade available that might help. I have a couple of things you can try based on what has happened to other posters who could not negotiate the best speed.
I know you have tried several cables already. Were they all the same length? A shorter cable might help (or not.)
Do you know if the router on your apartment's Ethernet jack is a gigabit or a 10/100 link? If the partner has a 10/100 link, you might be able to use a utility that changes the way the link is negotiated to force 10/100. You should read my answer at http://communities.intel.com/message/148594#148594 and try the utility. However, I do not have a lot of confidence in this particular change helping your issue. This does not sound like the scenario where the utility has helped.
Let me know if either of these suggestions helps.
I'm not sure if the link is 10/100 or 1000. Getting this information out of them would be near impossible. I would be willing to bet that it is 10/100.
I changed the registry key entry to 2 as you suggested. It didn't resolve the issue, but it did make it to where when I force it to 100 it simply registers no connection as opposed to a series and connects, disconnects, and lockups.
All of the cables are approximately the same length, 6-7 feet.
You could running the cable diagnostics that are installed with Intel PROSet.
Do you have a friendly neighbor that might let you connect to their jack for a test? You could test over a different set of wires.
Neither of these tests would fix the slow connection, but at least you might have some idea about the wiring.
Have you tried the drivers from ASUS? I'm not confident that a driver change will help, but you might be better off using the drivers ASUS posts instead of getting the latest generic drivers. http://support.asus.com/Download.aspx?SLanguage=en&m=P8Z77-V&p=1&s=39.
I was originally using the ASUS drivers. I tried the Intel ones only after the ASUS ones didn't work. I also tried uninstalling the drivers, clearing the CMOS, draining the power, and reinstalling the drivers. No go.
I emailed ASUS, and they recommended I do I fresh install (of everything I assume), and if that doesn't work, contact the RMA department. I don't think a fresh install of the OS, etc., will help anything. It seems like it just doesn't like negotiating with 10/100 switches/routers. So it's either a problem with the drivers or an issue inherent with this NIC. I really do not feel like installing a new motherboard, and further, is it even a hardware problem? If I was very confident that it was defective hardware, I might bother, but buying a stand alone NIC seems easier.
I can understand why you might not want to go through the hassle of replacing the motherboard without knowing for sure. Unfortunately I cannot tell for sure if you have a hardware issue. I did look at the bug database and did not see any open bugs or unreleased bug fixes that seem similar to your report. So I am leaning towards some sort of hardware issue. But that doesn't mean that replacing your motherboard will fix the problem.
In the original post you said, "A connection with a D-Link router seemed to work fine." If you have that router, maybe you could plug the router into the wall jack and then plug your LAN into the router. Maybe you are already doing that. Obviously your idea to add-in a NIC should work too.
I hate not being able to come up with a sure fix , but I can't think of anything else to do that hasn't been covered.