It's just the IMC on your particular cpu, I noticed the exact same thing on a cpu I tested and to double check we retested it on both the R5E and Killer with same results. It was impossible to train at even 3200 or 3000 and even the lower dividers would sometimes lose channels when pushed to tight or vdimm is to high.
Retested best dual core tonight, chip ran exactly the same as last time until I got the crack (using Gelid GC Extreme, ran out of Grizzly).
Need to figure out efficiency fail, on this OS or just roll a freshy.