Somewhat related, but I am running two kits of the 2x8 Ballistix Max 4000 dimms @ 4000mhz w/timings of 16-19-19-39, 1.5v, 1.25v sa,vccio. z590 aorus ultra auto's everything else. Can't lower tRFC or other secondary timings with errors. I notice that the sa and dimm voltage will jump up under heavy load to 1.51 vdimm and 1.271 sa. Gigabyte's override voltage setting is a mystery too me, and I have spent at least 2 days of screwing around with numerous voltages and dimm configs. Off topic, but 4 dimms and I hit 98c+ on2 cores, but 70c when only using 2 dimms running linpack. I hate to imagine what dual rank kits would do!