Network adapters not recognized/PCIe fails to initialize

I was having issues installing a Pro 1000 PT quad server adapter in the T5500 workstation. With the card in the PCIe slot the slot failed to initialize on boot. The card works as I have successfully installed it in a T3400. The slots in the T5500 are also operational - I can move the video card around to the different slots and it works just fine. The issue seemed to be the combination of the Pro 1000 PT quad server and the T5500 workstation. Changes to the bios have not resolved the issue and the bios does not recognize the card in the PCIe slot when it is inserted.

I already worked through Dell support and they were unable to help. So I went and spent money on a different PCIe network adapter (Trendnet PCIe). The same issue occurs! Any suggestions appreciated.