Dell T5820 PCI Slots disabled

Hi all, I have a T5820 which I'm having difficulty getting to recognize PCI devices plugged into any of the 4 PCI slots. The devices are a Dell DCWC300 NVRM adapter board, and a Startech PCIExpress Serial Adapter Card, both of which I have tested and are recognized in another Dell T3060 which I have, so I know they function. When they are fitted the Bios reports that the PCI Slots are empty.

I seems that somehow the PCI slots have been disabled in the Bios but nowhere can I find a setting to enable them.

Any help/suggestions would be most welcome.

NicP