Skylake cpu? Which model?
Assuming using 32GB dimms to use all six lanes (if Skylake)? This is something that has bit me a few times - most Skylake cpus have 6 lanes, so balanced is 192, 384, etc. Not 4 lanes like we are used to!
Would also recommend trying different ram configs anyways, on our side we have seen better thru put on 768 than on 384. Even 512 performs better in some cases than 192.