Has anyone else noticed that with all default settings, not even XMP applied, the Z390 Dark is hammering the 9900KS with voltage? With default settings, I'm hitting thermal limits within a few seconds when running Prime 95 Small FFT with AVX. Granted this is a stressful test, but yikes. 
 
I even tried re-pasting the CPU, same result. My idle temps are around 23c, but when it applies 1.477v under load...with default settings...the temps are through the roof. 

I have referred this post to EVGA

WOW!..That's extreme Vcore there.
 
Have you updated the BIOS to v1.07 from the EVGA Download Center which adds full support for an i9-9900KS and includes all the updates/fixes/enhancements from all previous versions..Do that if you haven't yet.

bob16314
WOW!..That's extreme Vcore there.
 
Have you updated the BIOS to v1.07 from the EVGA Download Center which adds full support for an i9-9900KS and includes all the updates/fixes/enhancements from all previous versions..Do that if you haven't yet.

this
 
Default settings always are on the high side .... decreases compatibility ..... Best to set them yourself
 
 
How are you trying to cool that CPU ?
 
Intel® Core™ i9-9900KS Processor (16M Cache, Up to 5.00 GHz ...
 
 
Use this:  Intel® Performance Maximizer
 
The Intel Core i9-9900KS Review: The 5 GHz Consumer Special

Well, that Vcore may not be as bad as I initially thought.

Upon further investigation, your Max. Operating Voltage (Vcore) is 1.52V according to the 8th and 9th Generation Intel Core Processor Families Datasheet Volume 1 on page 117 in Table 7-2..And in the Support FAQ: What is the Core Voltage of Intel® Core™ i9-9900K Processor and how to check the processor voltage?..That is at stock/default frequency.

Prime 95 is AVX intensive and I would not even use that at all, no way..That's why your core temps are through the roof, unless you set an AVX Offset to downclock the thing when AVX apps run..I would use the Intel Processor Diagnostic Tool or Intel Burn Test.
 
ADD: You set an AVX Offset in the BIOS.

360 AIO or Custom Loop are Needed for these space heaters

The max operating voltage is 1.52 that takes into account thermals. I'm obviously over that. 
I'm cooling it with a full custom loop that has two EK 240 PE rads. Fans are ML120 set at a fixed 66%. Pump speed is 100%. GPU (2080 Ti KPE w an EK block) temps are exactly like they always have been. 
 
You can't actually use the Maximizer with the Z390 dark. I have a post about that but the short version is that the Intel Watchdog Timer is disabled in the EVGA BIOS. The only workaround I have found is to use the XOC bios which can reveal MANY more settings and enable it in there. There's a couple of places in the XOC bios you have to turn it on. Then you can launch Intel XTU and verify that watchdog is on. 
 
I have tried this with 1.07 and the XOC bios, same result....very high voltages. Its unreasonable to expect someone to have to set a custom voltage just so they don't hit thermal limits on stock clocks when every bios setting is on default. The Z390 is overshooting the VID values by 125mv...with stock settings. 
 
This is within seconds of starting Prime 95 Small FFT with AVX. 
 
https://imgur.com/YCfEkO7
 

 
Same thing without the AVX.  
 
https://imgur.com/ArWMsJt
 

Just don't use Prime95..Or, add CpuSupportsAVX=0 to the local.txt..Or, apply an AVX Offset in BIOS..Otherwise, just keep hitting Prochot and maybe even Thermtrip..Intel won't guarantee a processor will recover from a Thermtrip event.

Oh my goodness!  I would've had a heart attack seeing numbers like that.
 
I'd also venture in getting the Intel OC warranty just to be on the safe side if you haven't yet.

I had the same issue with temps on my 9900K, not KS, until I went direct die.
 
Manual voltage adjustment is required, though.