So all 4x8gb ram work, but not together, I have placed them in all the slots at different times and work fine, I have even mixed them up on duo ie ram 1 with 2,1+3,1+4,2+3,2+4,3+4.
I can only get two to work together at any one time.
I had 2x4gb in previously so I even tried 2x8 and 2x4 together...