To even have overclocking options on a board as inexpensive as the ASRock AB350M Pro4 is commendable. Though options are limited, the basics are all there. My results were pretty much identical to those of the ASRock X470 Taichi Ultimate I looked at recently. I was able to get an extra 100 MHz out of my Ryzen 2600X at a manually set voltage of 1.35. Trying to add another 100 MHz again resulted in boot failure. So while the Taichi Ultimate offers a daunting array of tweaking options, it seems my chip is the limiting factor and as such, the ASRock AB350M Pro4 was able to keep up.
RAM overclocking told a different story. While the ASRock AB350M Pro4 has XMP support and manual voltage control, it does not have manual frequency selection. The ASRock AB350M Pro4 failed to post with the XMP profile of my G.SKILL 3866 MHz kit, and since I can't manually overclock it, I can't exactly find out where it's limits are. The ASRock AB350M Pro4 performs better than I expected for overclocking, but more thorough options for RAM tweaking would have been nice.