Mac Pro 6,1 Not Seeing New RAM

Hi, thanks in advance for any help. I bought my mac pro 6,1 as new old stock with 64GB of RAM in slots 3 and 4 by way of 2 x 32gb chips. I just bought 2 more 32gb DIMMS from OWC and installed them. No matter what I seem to do it only recognizes 96gb of the installed 128gb. I tried moving the modules all around, putting the old RAM in slots 1 and 2, but always slot #2 says its empty whether it has the OWC RAM in it or not. I tried resetting PRAM as well, but nothing. I reached out to OWC, but while i wait Im hoping someone here has a solve for this. Im scared it may be a bad logic board.