If it works without the NIC in but doesn't boot when you insert it then chances are it's a bad card. You eliminated the possibility of a bad PCI slot by trying it in difference slots. I'm assuming your motherboard doesn't have onboard LAN? You can pick up a new NIC for next to nothing nowadays
I have tried the Lan card in different PCI slots , everytime the card was inserted the system didn't boot.
I donot have an onboard lan on the mothrboard.
Will buy a new NIC & try it . Thanks for the reply