First I have 3600 Ryzen and it's the same as yours, although you have 3600X, it's all about that silicon lottery tho. My CPU boost clock is 4.2GHz and it gets to that, on all cores gets to 4.125 MHz, and I can overclock the CPU up to 4.3GHz with 1.3625v latest BIOS on MSI B450 Tomahawk Max MB - 1004 Patch B Bios. And 2 days ago AMD released new Chipset drivers for B450 Chipset
https://www.amd.com/en/support/chipsets/amd-socket-am4/b450 here download them and just instal them above what ASUS gave you, it will overwrite them with these new ones. If you overclock your CPU use High Performace in Power Options in Control Panel, and go in PBO and just enable it, don't add custom watts or amps currents just click ENABLED, that will do. I don't know why you bought the 3600x, it is just the same as 3600 but 40-50$ more money for bearly 50-100MHz that might work or might not. Silicon lottery again. I can say mine is kinda better on the silicon lottery. Although I use it now the 3600 overclocked @ 4.2GHz - 1.35v with 3200MHz ram. Oh and my highest score in C20 on 4.2Ghz was 3814 see what I am saying, and Single Core 514 on 4.2GHz PBO just ENABLED. But on 4.3GHz I got a score of 3911 and Single of 522 which is very insane. Don't have pictures at the moment to show you, but I will re-do and I'll post you images to see. It is all down to silicon lottery, you can find very good 3600X that might give you scores close to 3700X, crazy stuff ah?! But I saw that you said NOW with PBO you finally get your advertise clock speed of 4.4ghz, it should not be like that, AMD needs to give us the advertised speed, you should hit 4.4ghz on single-core from beginning and by adding PBO and adding that 200MHz + you should be able to squeeze more, on single-core, like 100MHz more 4.5Ghz or smt., but yes AMD is bad with advertised clock speeds. Make sure that you are on latest AMD ComboPI1.0.0.4 Patch B, BIOS cuz this BIOS was intended to boost the clocks for those CPUs that couldn't hit their advertised single-core speed, AMD just gives to the general public how much their CPU hit or could hit on single-core, there are not like intel, where intel tells you single-core XXXX this much and all core boost XXXX this much etc.