I got the 3900x on July 15 and already been a lot of bios updates (MSI X570 Creation). I tried all the bios, even the new beta bios with 220.127.116.11b (7C36v161) is not fixing the boost problem. The voltage control still horrible. My 3900x just won't go over 4.399Ghz.
Beside enable ram XMP, no other changes in default bios. The cooling system is Deepcool Gamerstorm Castle 360 RGB V2 AIO. Windows fully updated, all drivers fully updated. I using Ryzen Master to change and monitor.
My 3900x with PBO only able to get 509 points max in Cinebench 20 single-core test, the highest single-core clock recorded in Ryzen Master was 4.394 GHz, clock rate normally stays around between 4.300 and 4.350, and voltage around 1.49v (what a joke). In the multi-core C20 test, all core boost was 4.09GHz with PBO 7035 points), 4.05Ghz without PBO (6992 points). The voltage for the multi-core test was between 1.380v-1.395v.
Compare to older bios with older AGESA, voltage still so high, single-core clock rate still not reach marketing spec 4.6Ghz (not even close). The clock rate may be improved 25mhz to 50mhz in the default setting. The only thing massive improved is faster boot time!
The joke is my 3900x able to do perfectly stable with manually set all core to 4.3Ghz at 1.331v, in the C20 multi-core test achieved max 7560 points (low 7490 points), and single-core 512 points. Also, with 1.33v, my 3900x run much cooler at around 70-71C under maximum load (compare to the default setting at 76C). This setting I'm using since the first week. The awful default voltage control still awful after 4 months.
I'm very disappointed to AMD said they fixed the boost problem, however, 3900x at 4.3GHz still much much faster than my 5 years old intel 5960x. Maybe this is not software or AGESA problems for my 3900x? The best of my 3900x can do is 4.35GHz with 1.375v, but 4.4GHz no hope even with 1.49375v. (under load will black screen and restart).