AMD Ryzen 5 3600 auto boost stops around 4000-4100 MHz | TechPowerUp Forums
Dirt cheap Gigabyte B450 S2H is surprisingly capable of 3800 MHz RAM at 1900 FCLK (even official site only lists DDR4 3600 as a maximum supported frequency) : r/overclocking
Best Motherboards For Ryzen 5 3600: Budget, RGB, & Gaming