Is there any reason the minimum vcore adaptive target voltage on the EVGA Dark X299 is 1.2v? I've tried several different BIOS versions including latest (1.14) and it's the same 1.2v minimum for each.
If there isn't a specific reason (eg hardware limitation) I wonder if it could be lowered in a future BIOS release?
 
I recently got one of these boards for use with a 7980xe (delidded) and I would prefer to use the vcore adaptive voltage target for lower power consumption/heat at idle and AVX instruction, but ramp up at normal load.
I've got a preliminary OC dialed with the vcore override set to 1.115v, but can't migrate this to an adaptive setting, as the minimum selectable target voltage is 1.2v. 1.2v at load with this chip causes several core temps to get close to throttle point (running on custom WC loop with 1x 360 and 1x 480 rad).
I've tried using a negative offset in conjunction with the target voltage, but this causes instability in AVX/512 workload, as it's pulling the offset mv from the VID at all multipliers, resulting in too little voltage at the lower (AVX offset) ones.

What are you considering a throttle point?
What are you using for a block and TIM? Delided?
 
My 7940x - locked 4.8ghz - EK Evo block, delided,  currently with IHS in place with LM on chip and IHS
 https://forums.evga.com/FindPost/2829994
Radiators = 1x240 slim / 1x480
 
Temps have not been an issue - no CPU throttling
Current CPU settings
 

 
 
 

Radiactor_
I'm using a Heatkiller full copper CPU block and currently running direct die with Thermal Grizzly Kryonaut. 
 
On this chip, two cores (#2 and #12, 0 based) are a fair bit hotter than the others.
At 1.2v those two cores are spiking to 100C after several cinebench runs. Average over all cores is only 78C though.
I've also tested with the IHS back in place and temps are 3-5C worse on those two cores and 5-15C worse on others.
 
I'd like to use adaptive vcore setting for the power saving at idle, but the adaptive target voltage minimum of 1.2v is just forcing me to use voltage override to set an appropriate voltage for this chip.

are the screws tightened evenly on heatkiller cpu block?
try to run prime small ffts and see what the temps are.

Radiactor_
I've remounted the block (tightening bolts in x pattern) at least four times and those two cores are always the same, +/- 1C.
Temperatures by them self don't seem to be the issue, because when I set 1.115 override voltage (constant), the two hot cores don't go above low 80's in cinebench and approaching 90c in P95 sfft's.
 
I just think it would be good to have the option for vcore adaptive target voltages less than 1.2v

did you clean the silicon glue after you delided your cpu?
Might be your thermal paste.. if you want change your thermal paste to Liquid metal on IHS and see if the temp drops..
however your cpu block is gonna get corroded.

Mostly 1.2V min Vcore voltage is due to Intel CPU's VID programming range. When you have Adaptive Vcore it's not just simple X.X volts for VRM and CPU running that specific voltage at all times, but rather complex inter-operation between motherboard VRM, physical layout and own CPU power delivery regulator (FIVR). On software side there are three things that control voltages and power - BIOS code, PCU firmware (inside of CPU) and FIVR settings. 
 
In theory BIOS can program any voltage, below 1.2V including, but if that voltage is below CPU's own VID point for current running frequency then CPU will ignore setting you program and will settle to own lowest voltage. Also I don't see much reason why you want lower voltage, even if CPU could run it in some cases, undervolting would cause stability issues on heavy-loads/turbo clocks. There is not much safe margin between CPU VID and stable clocks to make a large difference. Great tool for testing this would be Prime95 (non-AVX older version) and AVX newer version as it stresses chip pretty hard.
 
Adaptive Vcore also does NOT mean cores will be running at 1.2V (or more) all the time, with default and even OC with adaptive Vcore setting voltage will be adjusted according to CPU loading, going down to 0.8V or lower, depends on CPU. To say differently: if you running adaptive and set voltage below what specific CPU have predefined from factory - voltage will be set by CPU, not MB BIOS. So we removed option to set below 1.2V at BIOS setup as it would have no effect.
 
CPU will only run fixed voltage if you use Vcore override setting and set it over what's CPU default voltage level. 
If you get good CPU (with plenty of voltage margin), I can recommend to try with Vdroop settings, perhaps there is specific configuration that can help you to maintain stability and let CPU run at lower voltages. Other point - you want to keep hottest die temperatures below 83C to maintain best performance. 

Wow, thank you so much for the explanation ! That makes complete sense.
And a big thank you to everyone else as well 
 
I've got an update re the high temps, as it looks like I've found the cause; the waterblock mounting bolts were tightened evenly (them being even was the problem apparently )
I pulled the block off again and re-mounted with different thermal paste (Arctic MX-4 I had left from a couple years ago), tightening the mounting bolts by 1/2 a turn at a time evenly in a X pattern. Upon testing, the two hot cores were actually a few *C higher than before and the others mostly the same. But, I had another suspicion (as you guys mentioned, the temps shouldn't be that high with the vcore in use) that the base of the waterblock or die surface might be uneven, so I started mucking around with loosening mounting bolts at bit at a time while running prime95 and watching temps.
I made some notes on which way temps were going on cores for adjustments on each mounting bolt and I managed to get all cores pretty close under load (bottom two mounting bolts needed to be looser than the top two, which resulted in the hottest three cores reaching 81*C, giving a 76.5*C average across all cores in Prime95 small FFT (non avx).
Do these temps look closer to what would be expected for 4.5GHz all core, 1.15v?
 

How do you have your following set, HT off?
 

I have experminting with these options.  I run my cpu at 4900ghz, with 1.280v, 2.0vin.
Wanna do 5 solid, and use adaptive, but strange is i set adative to 1.35 and offset of 75, to 
get at 2.75v on low, but always shows up in cpu id or eleet, 1.35, so where did the offset go?
shows under stress loads 90c, an didles at 38c, but still shows same vcore, so how does this
adatpive stuff really work, and do i plus or minus offsets? under adaptive?

So what is the purpose of offset? if it still shows 1.3v in CPU-Z? even with a 100 plus or minus offset?
And when i was at 1.3v with +100, it showed 1.39v in Eleet, and CPU'z.  So either under load or idle

Adaptive Voltage on Cascade Lake-X Doesn't work properly, Use Override.

Adaptive voltage allows the CPU to use lower VID at low load/idle.
So if you used the balanced power plan in Windows the CPU clock would drop as well as the Voltage, With Override the CPU voltage will not lower and will be locked at what you set.
 
Adaptive does work for the VMesh though. I use adaptive on that set to 1.25v

Well it should but it doesn't work properly as in it still will give you an undesirable voltage.

What did you set your adaptive offset too for the core?
Adaptive works as in the voltage will lower and raise depending on the load put on the CPU but from my experience it produces Vcore that is all over the place and at least on my chip it ran way hotter when dialing in the same voltage on adaptive vs just using Override and the same voltage.