The RAM issue may be because the BOIS is detecting at least on stick as bad.  Try pulling all of the RAM except for slot 1 on each CPU.  Check the available RAM.  Power down and swap sticks out and test again.  Keep doing this until you have cycled all of the RAM sticks through the number 1 slots.  The Dell Reliable Memory Technology will let you know if any of the sticks are bad.

Now if none where flagged as bad, re-populate all of your RAM and reboot, once again if there are any errors the computer will halt and let you know about which slot.  In the case of an error the computer will still work, but the available RAM will be reduced.  Try swapping a different stick in the flagged RAM slot and check again for an error.
If the error is on the same slot, you have a bad ram slot.
If the error moves to the slot the RAM stick moved to, you have a bad stick of RAM.

If the error goes away completely and your available RAM is correct, the issue was just a stick of RAM not quite seated completely.

I have never heard of an issue installing the Quadro 6000... Have you tried installing the Quadro drivers directly from Nvidia?