I can tell you on UEFI 0804 I can have 3466MHz with ease. I used:-
i) F4-3200C14D-16GTZ
ii) F4-3200C14D-16GVK
Both are 2x 8GB Samsung B die kits.
Double check you are using memory slots B2 and A2
i) I would set manually SOC voltage of 1.05V. Go to DRAM Timings Control, select Memory Presets section, load The Stilt 3200MHz Safe timings.
ii) On Extreme Tweaker page set Memory Frequency as 3200MHz.
iii) On Extreme Tweaker page set DRAM Voltage as 1.35V.
iv) On Extreme Tweaker page, within External Digi+ Power Control, set DRAM Boot voltage 1.35V.
v) Save and test.