Protective sticker on the cooler cold plate was properly removed? I didn't know screwing up that was a really a thing until recently.
Dark Rock 4, and not Pro 4?
Looks about right.
That cooler isn't adequate for this cpu under a full load like that.
Also, those auto voltages aren't helping... no worries, those are excessive on all boards by default - it guarantees stable clock speeds. Negative offset/adaptive mode tweaks would help that a little, but there's still the underspecced cooler.
Your voltage is boosting to almost 1.39v. (although, technically, 'VID' is the voltage asked for, not received, but I won't go into that)
The i9-9900k is a beast as far as thermals are concerned. You need to set a ceiling that is way lower than 1.39v if you have any hopes of taming it with your current cooler.
-0.03v. If it crashes, then -0.02v.
That -0.625v would be too much for offset mode, because it would also apply the offset on the already low idle voltage range.
Doing that much would work with adaptive mode though.
You'll get a few different opinions on how to tackle this and there's no 'one right answer'.
One way to do it is to override the voltage with a static settings and then adjusting LLC to let it 'give a little extra' when the CPU is under load.
You won't earn any points with the environmental team, and will probably spend a few dollars more per year on electricity, but setting it to something like a static 1.24v and allowing LLC to give some more may get it stable and within what your cooler can do for 10-15 mins.
As a side note, my system is not perfectly stable. Prime95, small FFT, eventually gets my i9-9900k above what I consider safe, but nothing else I run even comes close - so I'm okay with that.
Given the existing cooler (or while awaiting a larger one), you might be able to lower the peak turbo all-core clock speeds in 100 MHz increments in conjunction w/ experimenting w/dropping core voltage, all easy to do within Intel's XTU. (The above HWMonotr screenshots did not show what clock speeds were being hit under Cinebench, and, you did not mention if the clock speeds lower themselves after 30-90 seconds; I'd also make sure MCE is not enabled on whatever mainboard you are using, as you clearly do not currently have the thermal headroom yet)
I have the 9900K and the H100i Pro Watercooling CPU and even the H110i is not enough if I take any high clock high voltage situation.
I'm just stable at 5.0 ghz and 1.25V and temps are under control, anything over that and it overheats very quickly. I've had it booting and running at 5.2ghz, but stress it and the temps skyrocket and it dies.
IMHO, That little air cooler is just not going to get the job done w/ a 9900k processor. You need one of the AIOs, bigger is better with the 9900k.
The i9-9900, if kept at 65W TDP and run in mainboard that adheres to those standards, should indeed be fine; if, however, it is plugged into a Z390 that has power limits/TDP constraints/, and turbo duration limits all dsiabled, MCE-enabled, etc., it will run almost like an overclocked 9900K, minus perhaps 100 MHz, and, likely overheat...and quite quickly.
The 9900, given it's 65W TDP, should only run at all core turbos of 3.5 GHz or less after 30-60 seconds....; if it keeps higher clock speeds (4.6-4.7 GHz would be a dead giveaway to power limits being disabled) beyond that timeframe, then the mainboard in question is running with turbo duration limits disabled....
For the original poster...what Asus Prime mainboard is this?