AsRock Taichi x570-Strugling with Infinity Fabric

I think that 3600 CL 16 ans 3200 CL 14 is not so much difference.
I wonder if 14 14 14 14 28 timings are OK for 3200?

I hope, that this is right room for my question. Like you can see in the title, I have problems with setting INFINITY FABRIC to 1800 Mhz.

My setup:

CPU: 3900x, MOTHERBOARD: ASROCK Taichi x570, RAM: g.Skill 3600 Cl16 (16, 16, 16, 16, 36) (2x16G).

BIOS version: 3.40

Long story long :)

If I turn on XMP setting and leave all to auto in Ryzen Master I can see: MEMORY CLOCK 1800 and INFINITY FABRIC 1600. So no Couple mode.

SOC is 1,2 VDDP is 1,0979, VDDG is 1,0979 - In CPU-z is my uncore frequency 900 Mhz

If I in BIOS manually set Infinity fabric to 1800, my computer wont start. If I leave XMP and manually set infinity fabric to 1800 and manually set SOC to 1.2 and VDDP 1.1 and VDDG to 1.0 (last stable settings), I got popping sound through my speakers (in games). Very annoying.

Now I didn't use XMP and lower my ram speed to 3200 with CL 14 (14 14 14 14 28), and set Infinity fabric to 1600.

Now I have couple mode. My voltages in Ryzen Master are: SOC 1.150 VDDP: 1.0979 VDDG: 1,0182, CPU-z shows Uncore Frequency 1600

Everything is OK now. but I have 3600 CL 16 rams downgrade to 3200 CL 14.

I ques ASrock Taichi x570 isn't the best motherboard.

What is better:

that I leave XMP on and all on auto and I will get Memory Clock 1800 and Infinity Fabric 1600, and uncore frequency 900 Mhz - Originaly spec. of the RAM (3600 CL16) - NO CUPLE MODE

or that I downgrade RAM to 3200 CL14 and got Memory Clock 1600 and Infinity Fabric 1600 and uncore frequency 1600 Mhz?

Realy thanks for your answers.

Matic