Overclocking on Ryzen has not changed all that much since the last generation. It is actually quite easy to do.
The Ryzen 9 3900X has a base clock of 3.6 GHz and boosts up to 4.6 GHz. Now that boost is only on 1-2 cores. By overclocking we can set all cores to run at the same speed all of the time. This will give us better performance, especially in multi-core workloads.
We will be doing all of our overclocking in the BIOS. Once in the ASRock X570 Taichi BIOS head on over to the OC Tweaker Tab. First set the Overclock Mode to manual and the CPU Frequency and Voltage (VID) Change to manual. ASRock has made it really easy to now set your CPU frequency and CPU voltage all in one place.
I would suggest starting at the base clock of your processor and moving up in small steps. So for the Ryzen 9 3900X it would be 37, 38, 39, etc. You are likely going to have to adjust your voltage as well. A good starting point is 1.35-1.40V Vcore. Each time you overclock load into Windows and run a stability test, we use AIDA64 and CINEBENCH, but any CPU-focused benchmarking program would work. When running the stability test / benchmark be sure to keep an eye on your temperatures as well. If your system does not boot up try upping your Vcore. If that does not help you could try settings your load line calibration higher.
After much testing we were able to get our Ryzen 9 3900X running at 4.3 GHz on all 12 cores!
Our max temperature when running CINEBENCH R20 was 91.8C so this is not an overclock that I would suggest. You are likely going to want to bring it down to 4.1 GHz or even 4.0 GHz if you are using an air cooler.