Honestly as long as the CPU isn't getting near its max temps, idle don't mean a ton, and some CPU's to keep it at 30c or below at idle can mean for a louder system at idle as the fans got to work hard for really nothing but to make noise. 30c at idle is great, not saying it isn't its just there is a trade off. And I've had the 5800x, AMD kind of went crazy with the voltage on them at stock, they are hotter than they should be.
Its the max temps you want to really worry about, My CPU regularly idles around 40 to 50C at 20% fan speed, they are often at 800 - 950ish rpms its pretty quiet at a idle and little bit of load, I typically set my fans, GPU included to 100% at 70C, I sit around 50% fan speed around 60C, my board doesn't violent ramp the fans speeds up, but rather kind of slow so thats nice.
As long as you don't hit 90C and throttle, you'll be golden, Also 90C wont hurt the chip, thats a limit thats set, should start throttling its boost clocks to stays cooler, I'd look into a way to make it cooler though, but don't need to freak out if it hits it every now and then on like a benchmark or something, as long as your not sitting at it or it starts throttling below base clocks being its hot Then I'd say you have a problem you need to figure out. AMD aggressively ramps its clocks up on them, and the 5800x with 1 CCD in one little spot and more voltage at stock than that chip really needs, it will run a bit warm.
You can however make the 5800x consume quite a lot less power, mine I had was able to get it use less power than 5600G by playing with the EDC, TDC and PPT, lost no performance if anything gains a little bit due to having more headroom with power and temp, Might be worth looking into if thats something you want to do, I can't remember where I had mine set to as I sold that chip years ago but bunch of topics about it and some settings you can play with and benchmark.
Sorry if this is a bit to read, Good Luck!