I know this is a widespread issue among the Ryzen 3000 series, but here are my issues I have found so far:
Temperatures and core clocks in idle are very high in my opinion (52 degrees C) and 4,200 mhz. Because of this the fans go up and down in their rpm and it's very annoying in idle. Also the voltage is always 1.45V in idle, never dipping below 1.4V .
Also I have noticed my 3900X can't go higher than 4,200 mhz (where the advertised boost clock is 4,600 mhz) in a workload such as Cinebench R20 (my max score was 6912), PBO only, no manual overclocks.
AMD Ryzen 3900X
Noctua DH-15 with Kryonaut thermal compound
ASUS Crosshair VIII Hero Wi-Fi X570 Motherboard
Kingston HyperX 2x16GB 3600 mHz CL17 RAM
Samsung 970 Evo Plus 512gb SSD
Asus ROG Strix RTX 2080 GPU
Running on Windows 10 (1903) with latest updates, latest AMD X570 Chipset Drivers, latest Crosshair VIII BIOS update, everything up to date.
Also tried switching between all Ryzen power plans, and only used one monitoring tool at a time (Ryzen Master or CPU-Z)
multi core usage will never boost to max 4.6, if you getting 4.2 is about right for multi core. As to 4.6 boost you might only see that in single core bench and for a very short time. Try running single core test.
i've dissabled PBO where ever i can find it, and tried all the powerplans as well (had to use some program that i barely understand to mess with some hidden power plan things to get it to idle somewhat reasonably (1.1-1.4v when it's called for) before i had 1.45 all day every day (unless i hit it with a heavy load then it would let it go a little lower)
wile occasional 1.5v might be oke i'm not entirely sure idling all day at 1.45v drawing 145w sitting on the desktop picking my nose is working as intended : / on that subject i've seen linus's crew get a 3900x to idle at 0.3v on a asus board...how, mine in normal decked out windows will not relax off of 1.45 unless i mangle the powerplan, and even on a bare fresh windows it never dropped below 1v
(using a asus X570 strix-E, first amd build..ever nice performance, why won't it stop boosting)
way ahead of you, doing some investigating 1 process that comes on a fresh windows is lighting control (control's asus rgb puke) i axe that i idle at 0.5v with the ryzen power plan stock as is...granted i've axed everything i possibly could but i'd say the cpu needs some more relaxation training, with lighting control running i idle at 1.1v from that 1 process running, i start icue i'm sitting pegged at 1.45 granted these programs need to adres this but i feel this should be a 2 way street i'm really not confortable having it sit at 1.45v hovering between 50 and 60 degree's with the boxed cooler, granted i'm about to watercool it but that just hides the problem that's still there. as is even if i axe icue i'm still pegged at 1.45 as i guess something else is triggering it. but it is nice to know my cpu can do below 1v...it just doesn't unless i run the barest windows there ever was : /
though... i'm now bringing things back 1 by 1 think i've got practically everything and it's still flexible in it's voltage...now operating in the 1.2-1.45v range due to the background processes but not pegged at 1.45...not sure why not....
powerdraw also dropped from atleast 28% to 23-24% (went as low as 17 % with everything off) i'm quite confused but pleased with the progress.
Latest chipset driver from amd, a fresh install of windows and no software from asus (such as the lighting control) on a ryzen balanced power plan seems more normal now. Now most of my cores are asleep in idle, clocks are 800-1200 mhz and voltages are around 1.1-1.3.