Aurora R1 - Max Memory/Speed

I have an old Aurora R1 i7 930 with 3 memory banks.  What is the maximum memory and memory speed I can use?  I know I can run 24GB at 1333, but how about other configurations?  I have been told the max memory support gets halved for each step faster by dell, and that 1866 MHZ is the max speed.  I have also been told I can run 24GB of 1866.

E.g. can I run 12 GB (or more) of Corsair Dominator (1866 or faster?)