Unable to POST on Gigabyte P67A-UD5 inserting PCI video card

I am having Gigabyte P67A-UD5 from past couple of days. Well I am not able to POST my motherboard after inserting PCI video card. the computer is getting entered into a boot loop, powering on and off again and again. I am using couple of graphic cards to get the 4 monitor setup by making use of PCI-E and PCI video card. my system is getting POST only when Nvidia PCI-E 9800GT is inserted. However after inserting Nvidia 9400GS PCI or Nvidia 8400GS PCI boot loop is starting. As far as system specification is concerned I am having i7 2600k, 16GBCorsair Vengeance RAM.
Let me know if you are having any useful information to resolve the matter.

Ok you have provided all most all the information except PSU. Can you tell me which PSU model do you using? How older your PSU is?

I am using Antec Neo Power 650 watt. It is around 2.5 year old. For your information I tried to resolve the issue by replacing PCI 9400GS. I don’t know but due to some reason this particular motherboard is not able to boot up by inserting PCI video card. now I am using couple of PCI-E cards in order to achieve 4 monitor setup. I have inserted one at 16x slot for the main displays and another one is at 4x slot for extra screens.

Well I am suspecting that BIOS is not able to get another PCI-PCI bridge. Hence it is not able to allocate space for BAR. Could you will need to install latest version of BIOS on your motherboard. You can get the same from the official website of motherboard manufacturer.

I think there could be something wrong with the motherboard itself. So I recommend that you should contact the technical support team to get the further help on this particular matter.