I had 2x R7 1700, same country but differing batches, 1st UA 1706PGT vs 2nd UA 1709PGT. So UEFI defaults with x264 loading CPU, 3.2GHz ACB shows VCORE: ~1.089V SOC: ~0.838V vs VCORE: ~1.119V SOC: ~0.893V. Both OC to 3.8GHz ACB with +137mV vs +162mV.
UEFI v1002 was used on C6H with F4-3200C14D-16GTZ, same all other hardware.
1st only capable of using strap 2933MHz 14-14-14-34-1T, 1.35V VBOOT & VDIMM, SOC is 0.900V in UEFI (~0.901V on DMM). Increasing VCORE to +181mV and SOC to 1.050V yields no 3200MHz, may that be [Auto] timings or manually set. I get Q-Code 15 and sometimes 15 turns to 0d, the Q-LED for RAM is also on at that time.
2nd is using strap 3200MHz 14-14-14-34-1T, 1.35V VBOOT & VDIMM, SOC is 0.950V in UEFI (~0.966V on DMM).
As I no longer have the 1st CPU I can't test it with the new UEFI for C6H which has AGESA 1004a. From what other members on another forum have experienced some are still struggling to gain 3200MHz on single sided 2x8GB configs. I have also noted several posts by members where they do the same as I did above and they gain higher speed RAM.
Either some IMC/DF due to immature FW just "hiccup" with high speed RAM or there is variability between the CPUs.
Even "X" CPU does not mean guaranteed high speed RAM IMO from posts I have read,
one such example link.