Ok, So I have a x299 dark, Ive been running bios version 1.23 for a long while and had no problems . So after reading about NVIDIA resizable bar I wanted to try it . (thanks to evga for enabling it for x299 users)   So I downloaded the latest  bios 1.28 and flashed the motherboard. It flashed and everything seemed normal,resizable bar is now in the bios. So a day later I booted up the pc and heard it beep 3 or 4 times and it had a d3 code... looked it up and this is what it says (Some of the Architectural Protocols are not available) very helpful . its got the code twice now but other then slowing it down on booting up it doesn't seem to effect the pc at all.
 
Today I booted the computer up and I hear 3 beeps and see a d6 code () D6 indicates No graphics output. Motherboards and CPU's that do not support integrated graphics will need a graphics card installed) well thats nice but I never had a integrated gpu .... and after displaying the code the pc boots normally.  I never had these code with bios 1.23... they only showed up on 1.28 that's the only thing in the system that has changed .
 
Has anyone had similar problems with bios 1.28? or am I just lucky? systems  is a I9 7920x , evga 3080 ftw3 ultra, evga x299 dark and g-skill 3200 mhz ram.

Well now I'm getting a d6 error on every cold boot followed buy 5 beeps .....  again I never had these codes pop up ever until I upgraded to bios 1.28.  So its ether the bios or my barely week old 3080..... but I never saw this code even with the 3080 installed with 1.23.
 
And I was just curious about resizable bar. It gave me 3 hole fps on horizon zero dawn lol.

Well I tried bios 1.26 and that didn't go well. The d6 error didn't rear its ugly head but other problems showed up.  after configuring the bios I notices a Os loading bar I haven't seen since windows 7 show up. Computer was much slower to boot and I'm not able to get into the Bios . It just sets on a blank screen with a flashing cursor. Had to clear the Coms to even get into the Bios . I think it was the resizable bar or above 4g decoding causing the problems . They're enabled in 1.28 and I don't get those issues... just the d6 code. So I'm back on 1.28 with fast boot disabled maybe that will help.  If not then I'm stuck dealing with the d6 code or its back to 1.23 for me

Mister E...
I've got a x299 Dark with v.1.28 installed (Rebar enabled on a 3070 Ti).
 
I experience the 5 error beeps and (temporary) D6 POST Code if I boot the PC from an off state and have my monitor off as well - just need to make sure my monitor is powered on first before powering on the PC.
 
When downgrading a BIOS, it's a good idea to reset the CMOS settings (most even recommend that when updating) - especially in this case as you've enabled an option/feature that doesn't exist on the older version BIOS and the last saved settings (with the newer BIOS) have it referenced if you didn't clear/reset).
 
Also, don't forget the x299 Dark has got 3 BIOS chips - you could always try changing to one of the other chips for a different version (perhaps your old v.1.23 is still present on one of them?).

 
Well its much better with fast boot off, Its only gave me the code once so far, before it was every time I turned on the pc or restarted the pc. I thought about the switches but I wasn't sure when you flash the bios if it flashes all of them at the same time or not.  And Yeah I tried to clear the coms didn't help. I cant remember for sure if the monitor was on when I turned the pc on or not.... Ill have to notice more often but regardless I never got the d6 code with 1.23.

So I found out if the gpu is plug up with hdmi I also don’t get the code …. Very odd bug, but doesn’t look like I’m going to get any answers from evga on wether it’s a bug or not …. I think the fact that it’s only showing up on the newest bios and not the older one tells me it is . Oh well . As annoying as it is , at lest it doesn’t keep me from using the pc .

ZoranC

sazabizc
Very odd bug, but doesn’t look like I’m going to get any answers from evga on wether it’s a bug or not …. I think the fact that it’s only showing up on the newest bios and not the older one tells me it is.

Have you opened the case with EVGA? If you haven't it is not likely you will get an answer from EVGA because posting in forum doesn't constitute official request to EVGA for an answer.
 
FWIW, I'm running X299 Dark on 1.28 BIOS with 2080 Super connected on DisplayPort and in general haven't experienced problems booting/using it. However, I did have a period of intermittent issues that seemed to start when I had Above 4G Decoding enabled and went away when I disabled it.
 
Above 4G decoding is one of requirements for your ReBAR but in my case 2080 Super doesn't have ReBAR and my Dark's BIOS ReBAR setting was off so it couldn't have caused issues I had, only setting I was flipping was 4G decoding.
 
It is my understanding that correct functioning of Above 4G decoding depends not just on mb's BIOS handling it correctly but also rest of components in system, including their drivers, doing same. So it is possible that it is not (just) the mb's BIOS impacting you and me.
 
In the end I decided to keep above 4G decoding off, any benefits I was perceiving were small and not worth the hassle.

Ive tried to turn off rebar and 4g decoding and it still gives me a d6 error if the monitor is off as it’s posting . But oddly enough doesn’t seem to care if hdmi is plugged in and monitor is off . Only get the code with display port .

ZoranC

sazabizc
Ive tried to turn off rebar and 4g decoding and it still gives me a d6 error if the monitor is off as it’s posting.

Hold on a sec, I was under impression you earlier claimed you have started having your "issue" -only after- you updated BIOS from 1.23 to 1.28, that everything was working fine with 1.28. As far as I know that is -NOT- possible. I've used 1.19, 1.20, 1.21, and 1.23 BIOS-es and they -ALL- behaved in the same way: If monitor is off / not connected you -WILL- get warned about that. If I forget to turn on monitor and I am booting to Windows all I need to do afterwards is turn on monitor, shake the mouse and sync with monitor will be established.

Yep Only show up on 1.28. And the monitor isn't unplugged, its just off . If I  have the Monitor off but plugged in to the gpu before the pc post. I will get the d6 code. On bios 1.23 and a really old version I forget the number.. I do not get the d6 code if the montier is off before the Pc post. On bios 1.23 and older the pc doesnt care if the moniter is off or on while its posting. I get no d6 code.

I have googled the d6 code, and base on what I understand it mean the motherboard couldn’t find the gpu…. And I have tried a 2080 super in the board doesn’t change anything. I also have a evga x58 motherboard and never seen a d6 code on it .

Just seems odd to me I’ve never had the d6 code until I flashed bios 1.28, if I use the bios switch and go back to 1.23 no d6 code . And if I switch to the oldest bios the one my board came with (might be 1.12 can’t remember for sure ) no d6 code . So I don’t know what’s going on. Guess if I want to fine out I’ll have to contact evga .