Hi,
 
I recently put back together my rig with my X79 dark and my i7 3820, I left all of the bios settings at default except loading the XMP profile.
 
All of the voltages have been left on auto.
 
I decided to give overclocking the 3820 a go,  But I noticed that prime 95, AIDA 64 and IBT all fail with the stock settings.
 
I haven't really noticed any instability while using the rig, but if all of the stress tests fail that kinda makes overclocking hard no? 
 
Here is what I have in the rig,
 
EVGA X79 Dark (Bios 2.13 I think?)
Intel Core i7 3820
4x4 GB 1866 MHz G.Skill Sniper Ram
Sapphire Nitro R9 390x
EVGA G2 750W
 
I'm using a noctua NH-U12S temps are in the 50 - 60 range.
 
With voltage set to auto CPU-Z says I have a core voltage of: 1.176v under load.
 
Not sure whats going on here.
 
Maybe not enough vcore?  But ive never really run into a setup that didn't function correctly at stock on auto.
 
Edit: I see someone on another forum mention they get 1.25V as the default vcore on a X79 sabertooth when they reset the bios.

thanks, if i don't touch the memory settings it seems to be stable now.
 
However if i set my vcore to 1.24v in the bios I noticed the upper left corner says 1.25v and CPU-Z / HWmonitor say 1.22v with no load and 1.20V with a load what is the real voltage? 

When I had my 3820 and X79 Dark board, I never could get total stability with my ram set at 1866 using the XMP profile or manually.  I just always figured I had a very weak IMC.  The chip itself was a good OC'er though.  Once I settled on leaving the ram at 1600 using the XMP profile timings, all was good.
 
While I OC'd using the bclk, I had no trouble with the ram (or stability) anywhere up in the 1600 to 1700's.  Just not 1866...

I never really paid much attention to the VID voltage.  I also always used a fixed Vcore voltage on my Dark board instead of an offset.

I gave an explanation on Vdroop in your other thread.  At least as far as to what I experienced trying the various Vdroop settings...
 
If you want some idea's for some settings, here's what I was running for my daily use.
 

 

 
Here's my 4.80 OC main settings  >>  http://forums.evga.com/4808-GHz-with-BIOS-R210-m2129272.aspx
 

The K-boost feature gives you a short quick boost of vcore voltage at boot-up.  It's nice if you're able to run a high OC at a lower vcore, but it won't allow you to boot at that same vcore.
 
I always tested my OC settings with K-boost disabled.  If I was stable, I didn't use it.  I don't see any reason to use it as long as you can boot with whatever vcore setting you're using.