Hi @johndoe52944
After some research, it appears your RAM is ECC, while the board you're using doesn't support ECC. ECC is for correcting corruptions, but is not very important on a gaming machine.
It is possible this could be limiting speeds, but it is not the only reason. You can try using non-ECC memory to see if this fixes your issue.
These issues could also be due to a bad memory stick or socket, so you should try one stick at a time in each sockets as a first step to troubleshoot the issue
Hope this helps.