onboard nic not detected

we are using intel motherboard s975xbx2.
the problem is that when machine boots up. Gigabit NIC does not show up in network connections though in the device manager it shows up, in properties it says there are no issues with hardware.
apart from built-in NIC, we have got 2 external gigabit NIC's which are working fine.

rebooting doest help either
it shows up sometimes after complete shutdown of the system, but again goes off with the next.

what could be matter with inbuilt-nic?
have tried updating driver but no use.
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i would test it on another Os, like a live knoppix cd, to check if it is ok or not :
ftp://ftp.uni-kl.de/pub/linux/knoppix/KNOPPIX_V5.1.0CD-2006-12-30-EN.iso      Knoppix      
It looks like the onboard NIC is break down / damage ...... no choice, if want to repair replace the motherboard is the way to go ...... Or you just plug in the PCI / PCIe NIC in order to save the cost ..... Good Luck !!
Does the onboard NIC work (just the Network Connection icon thats missing in the CP?), or does it not work at all....

How to troubleshoot missing network connections icons in Windows Server 2003 and in Windows XP

"Network and Dial-up Connections" folder icons missing

Use the first article first. Never really have an answer that is a specific step that works, but usually by the end of the article it is fixed....

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