Problems running dual video cards

Hi,

I have this bizarre issue setting up a dual card setup on my uncle’s Gigabyte GA-K8VM800M MB. This MB has on board video and he wanted to add an additional PCI videocard to get a dual setup. When he tried that all he got was a green box appearing on the second monitor, first monitor was displaying correctly. We then tried two PCI cards and the second monitor still had the green square, 1st monitor was hooked up to the other PCI card and was blank. When we tried an AGP card, the on board video was automatically disabled. I’m wondering if this will only work if you have an AGP and a PCI card hooked up. We are going to try this but has anyone seen something like this before? We have tried the second monitor out on the on board display and that works.


Thanks in advance