Can't exceed 2800MHz RAM speed

The RAM may be able to do 3200MHz, the CPU may not. Remember that the stock RAM speed for Ryzen 1xxx CPUs is 2667MHz and anything over that is an overclock situation for the CPU memory controller (although strictly speaking enabling the XMP profile is an overclock for the RAM as well, even if it's supposed to be able to handle the XMP speed). In any case, it's really a lottery that involves the CPU, the motherboard and the sticks themselves. Sometimes they just don't care for each other, sometimes they work together like a charm. Now, since you saw some progress changing the SOC voltage, you might be able to push at least beyond 2800 MHz by tweaking the voltages. My suggestion is to set SOC voltage back to auto and RAM voltage to 1.4V (just like gizmic said), then increase the RAM speed to 2933 MHz. If that works, increase the speed to 3000 MHz and check if that's stable. If not, set the SOC voltage to 1.1 V and see if that stabilizes the memory. Also, I'd still try setting the CPU voltage manually. The voltages can be all over the place with the auto setting, which may make matters worse, even if it doesn't directly affect the RAM or the IMC.