[ixp1200] Network Cards' Compatibility with the Octal ports of IXP1200

hallo, I have some network cards that seem not compatible with the octal ports of the IXP1200 ie. the LEDs show an orange-colored signal when connected using those network cards and not the green-colored indication. I have 6 working 3-Com cards, and all have that same problems. I also have 2 similar working Xircom cards, one gives a green-colored signal and the other not. It has been traced down to be the problem of the network cards and not software or PCI planes. Does anyone have any idea, why ? Thank You and kind regards, cheewei