Dual Graphics cards error

I recently installed a second graphics card to get triple monitors, but the second card is giving me the "Error 43" message. Both cards are GeForce 8400 GS (one PCIe, one PCI). I am not attempting to run SLI or anything like that, just want the triple. In the device manager, both cards are listed, but the 2nd one has the yellow error icon on it. When checking the details, they both have the same version of the driver. I am running Vista Ultimate x64.

Where am I going wrong?

Can you run two cards without SLIing them? Didn't know that Where did you get the drivers from? Try to download them for the nvidia website.. Search that error code in google, see what other people have come up with.

Amplid

http://www.microsoft.com/whdc/device/display/multimonVista.mspx

The error code means, that there are non-identical drivers installed for the cards..

Amplid

Yeah, I've poured over that document numerous times, hence my confusion. I downloaded the driver directly from Nvidia, and the device manager indicates that have the same driver.