bilbat :
OK - got indepenent confirmation from the 'linux guys' (who typically know their hardware) - the lan drivers install from the nVidia chipset stuff; my guess - unlike nearly every NIC since the transition to GLAN, this one doesn't simply 'attach' to the chipset's PCIe bus. What normally happens is you install the chipset drivers, they activate the PCIe bus, which then 'exposes' the NIC to be discovered to 'want' drivers; obviously (and inscrutably, as nVidia does not release documentation), the nForce is doing something else, that is effectively 'hiding' the LAN chip's interface...
Many thanks to you and others for trying to help me.
In the meantime I have managed to find solution myself!!!
If you use default Bios values LAN part of NVidia chip is disabled at does not show in device manager!
With LAN set to Auto it loads driver and subsequently shows as LAN in Device manager!!!!!When you load default values it again disapears from Device manager. My previous Gigabyte board did not have this problem and that explains why I have did not look at BIOS settings before installation and did not even think (like many others including you guys) that if something does not show in Device manager it is just because it is disabled in BIOS.
So just to sum this all up.
Your "linux guys "are right.Realtek device does need a driver,driver is included in NVidia chip drivers, but unless you set BIOS LAN to auto you will not have LAN in Device manager!!!
No wonder others are having problem with this type of LAN setup. It is so tricky (or stupid?)
It would help to mention this in Manual for this board.