Interesting note - the Realtek 8111E drive on my mobo that was having the problems, showing Half Duplex support for full GB, check on a Windows 7 system that uses exact same setup (both boards/cpu/ram where purchased at same time). Windows 7 only show support for GB at full duplex - no half duplex option. So, I wonder if it isn't so much the chipset itself, but, the driver included in this version? Might 5b6a have a better drivers? Might the driver support for Realtek just not be that great?
Since gone with the PCI-E NIC, not a single issue...
Shawn