1) Try avoid posting in all CAPS, as it states yelling.
2) Does it show up in your Device Manager (you might have stated this but not clear to me)?
3) Does the card work without the 8800 GTS or 9800GX2 installed? If not, it is a card issue so look to RMA.
4) Does it show up when in the 1st (closest to CPU) PCIe x16 slot and the 9800GGX2 in the 2nd slot?
5) Why in the world do you want to mix three cards? I believe the Nvidia Control Panel / Drivers can only support two different cards, not three, as you are trying.