Are you happy with BIOS 3.30 with regard to overclocking?
Did you use a previous version?
Is 3.30 more stable with same OC settings?
I have the same board, delidded 8086k.
I'm on BIOS 3.10, and to preface this, I won't likely buy another AsRock board.
They have the worst customer service, they don't answer in their own forums and even sub forums like here and tweaktowns, they ignore their customers.
Their adaptive voltage is absolute trash when you are looking to push a CPU to it's max (delid etc), and when you are pushing 5.3-5.4Ghz (what I'm running on the 8086K, all cores, no AVX offset), so fixed LLC1 is really the only way to get stable, at least on BIOS 3.10.
I use small 40mm fans to actively cool the VRM/MOSFET's, which is important when you water cool, you have Noctua air cooler so you are good
That being said, there is something you might want to look at in your OC quest.
Using HWInfo64 you will see that this board has 2 entries (in sensors) for Renesas ISL69138 controller.
One of these sensors is wrong, you can see that it's wrong, so hide it.
You can easily tell which one is correct as the first value 'VR Loop1' will correspond to a CPU Value 'VR VCC Temperature(SVID)' - this is essentially the VRM/MOSFET temperature sensors.
If you have a 'fixed' vcore in BIOS, the value below 'VR Loop 1', a value named 'VR VOUT' will be very close to the 'vCore' setting.
This 'VR VOUT' value is essentially a more accurate reading of the real voltage that the core is requesting from the VRM/MOSFET's - there's a lovely technical reason for this which involves resistance in circuitry that means 'vCore' is not the most accurate reading, and that's really all you need to know.
The author of HWInfo and AsRock have confirmed this sensor is indeed correct and should be trusted as a more accurate reading of core voltage.
As other's have pointed out (kinda in a roundabout way), if we are looking at fixed vCore, due to vdroop it's impossible to have the same fixed idle voltage as under load voltage.
And the higher the OC, the more voltage you need to push.
With Fixed vCore and LLC1, you will typically see idle voltage about 30mv higher than full load, such as stress test with Realbench (also my favorite).
So let's say my idle vCore at 5.3Ghz is 1.415v, under load the vCore value in HWInfo will pretty much stay the same, with occasional dips to 1.406v.
BUT, the VR VOUT value will be in the 1.386v area, which shows just how much variance there can be, and why even the tightest LLC on this board is still trash.
High voltage at idle is NOT dangerous in terms of killing your CPU - within reason of course. If you have nice cooling, you can sit at 1.45v at idle, with 1.41-1.42 under full load.
High idle voltage will barely draw any current (amps) or power (watts) - Coffee Lake processors are good for 138A/180W continuous, which even under stress testing conditions is very unlikely. You might see spikes, but not constant.
On the other hand, what can damage or degrade a CPU is High Voltage combined with High Current and High Power,.
This is why I've always used fixed voltages, and always turn off all C-States, Speedstep(EIST)/Speedshift - my PC's are primarily for high performance gaming, so I could care less about saving a few dollars a year, and quite frankly the environment has WAYYY bigger issues than me drawing a few more amps per month than another PC with max power saving settings.
There's many who have the opinion that higher idle voltages kill CPU's, but if you have good cooling and keep those temps in check (I'm at max 72C after 4 hours Realbench) then you will replace your PC long before your CPU degrades.
Now, if you are running vCore at 1.5v, then you will likely see degradation during the life of the PC, but even then it's still not a fixed science.
Stay under 1.45v idle and good cooling and if you replace your PC every 3-5 years you will most likely have zero issues.
I have never had a CPU die on me, 30 years of building PC's - and I'm not alone
So, this may help you feel a little more comfortable about raising the 'vcore' value in BIOS, because your under load value on this board is going to be quite a bit lower, and that's the one you really need to care about.
BTW - would love to hear if you like the new BIOS better.
I'm thinking of going back to 1.20 before all this Spectre microcode crap that has impacted performance, but most likely tossing this board in the trash.
Cheers!