Nice that its CL13. The other timings can help you reduce vDRAM and keep that performance. With CL15 tight secondary etc timings. 1.44 volts vDRAM in BIOS. VDDP set to 0.88 volts. I would keep things lower than 1.5 volts vDRAM. The maximum for xmp is 1.5 volts.
I would add to above, lowering SoC will affect other voltages as well. Some can't be higher than the SoC voltage. Also in the bios there is overclocking voltages. SoC, VDDP and VDDG are there. In Ryzen master you can see their values.
They are at stock, 1.1volts for SoC, CLDO VDDP 1.09 and CLDO VDDG 1.09. Now if I set SoC to 1.05volts there, in Ryzen master that voltage is 1.05volts. Also if I set CLDO 1.009 for both CLO VDDG and VDDP. When I get restarts or issues in vray that is better that setting the bios VDDP value to 0.88volts. Note the best settings I am trying to keep things stable at IF is keep CLDO VDDP and SoC under overclocking at auto. In ryzen master this means both SoC and VDDP are 1.1 volts. I have changed VDDG to be approx. 40mV below SoC. That appears so far to get rid on sound cracking and restarts with vray. I will need to test more.
So in BIOS after updating to ABBA. OC Treaker, CPU configuration. There are two new added value, CLDO VDDP and VDDG. SoC/Uncore OC voltage was there before (see video). So IF 1900 becomes unstable with the ABBA update. Changing CLDO VDDG appears the affect the issue. I have 1.06mV set atm.
ASRock X570 Taichi BIOS Overview
https://youtu.be/hus0u-jX6nc?t=108
When you run stress tests the CPU drops to lower more stable values and you get zero issues. So the only way to make sure you are stable with the stock boost working is to just use your PC. So it takes time to get things stable and find what works best.