@Ntrako - thanks for clarifying, something to do with your XMP then maybe, or possibly use of XMP in general, either way best to redo BIOS so it doesn't happen, like we did. That explains why others maybe didn't notice any issue, if not using XMP, or maybe if their XMP didn't cause issue etc.
No matter what, best we redid so issue does not happen, better for everyone that way, which is why once we solved source of problem and fixed it I then removed all previous BIOS and tagged everyone to update to new mod.

@Lost_N_BIOS
Υou are very patient person when you listen the problem(personally the problem i had) and by the fact we were trying both to find where the issue came from, it means that you are responsible and prone to what you do.
All i wanted from a lot of PMs with you was to resolve the issue for 2 reasons: The first was to understand both were the issue come from and the second to have the best possible result.
And we(basically YOU) did it. I believe you are now better with your knowledge instead before because you learn about all of it by yourself(i mean about the issue, you had already knowledge about the proccess).
Very big thanks to you,
I am student in University in computer science and you just read all the above message from just a student.
Sure your work must be appreciated for all the time you spend for me(and the others),
I dont have job right now, but sure i will give you a donate when i have money.

PLEASE READ IT, DON'T SKIP:
One Message to all the others who are asking for help in forums like that,
Please don't have the idea that all successfull requests which are done and free, zero time is dedicated.
Someone spent lot of hours to assist you,
So for all of you who have money, JUST DONATE to these people, they deserve it.
Τhe work they do for us is not as easy as you think.
Thanks all of you for reading this message.

@Ntrako - Thanks! I agree with you, I wanted to find and solve issue too, so it had to be done
Yes, it does teach me when things like that happen, next time I will be able to recognize when this happen by user comments, and then quickly know how to resolve without a lot of testing needed like we/YOU did
I appreciate all your kind comments, thank you! You don't have to donate anything to me, but if you ever did want to, then please send me PM and I will tell you how.

Yes, mod BIOS is not easy always, and often it's never a quick process unless you are just doing something simple with a AIO tool like UBU.
Thank you for your final comments, they are very heartfelt to me, and I appreciate you taking the time to share your thoughts about all that to possibly encourage others to pitch in when they can

@Lost_N_BIOS Booted and working (my 4801 with updates and no bifurcation, Post #97).
Here's FPT image : LINK
Yes, both BIOS and HWInfo64 show "42E" as uCode used.

Thanks for confirmation it's bootable, and ucodes are correct, you are lucky this time. That BIOS has two padding files removed at uCode modification edits, often this = bricked BIOS, or non-load of proper microcodes, but as you see here not always
Are you sure Windows didn't load the 42E? Can you test some other, as a quick test, to confirm this aspect is OK and that 42E isn't applied by OS, before I move forward with your mod as base.

?
@Lost_N_BIOS When I wrote Windows didn't load 42E with my mod ?
...
It does load no problem :

@agentx007 - Sorry for any confusion. I meant, if BIOS has old, or non-loading microcodes, then windows will load it's own (especially win8-10)
So, I meant for you to test, inserting some older microcode so you could see if that version is applied or if it still shows 42E. Also, unsure if this matters or not, windows may do it even if not connected to internet, but be offline in case windows can only do that if it sees old/none while online at first.
Example - If it still shows 42E and you inserted 41D for example, then we know what I mentioned is causing non-load of microcodes from BIOS

@Lost_N_BIOS Since Windows doesn't have 42E update for Ivy Bridge E (newest uCode update for Windows : [LINK] lists "42D"), how it could use 42E if BIOS uCode on MB itself was screwed up ?

Sorry, I don't keep up with that, only know that windows can do this and stuff like you linked may not always be the final thing windows 10 is doing today at this hour without our permission
If you want me to move forward without proper confirmation I can? I guess I will, since you've waited so long, for which I apologize. Please wait little more, I will make these for you today/tonight

* Edit - @agentx007 - sorry, at post 178 I confused C/D. I will do C here (no bifurcation, as you sent me) and then you test the issues I mentioned about memory/VCCSA, only noticeable with the use of XMP pointed out by Ntrako
Then if all is OK, I will take that BIOS and add the bifurcation mod to make D for you. Here is C for now (4801 no bifurcation) - http://s000.tinyupload.com/index.php?fil...152271445251606

It appears your BIOS bricked my x79 sabertooth board. I was on 4701 bios before, bought a PCIE nvme controller so thought i'd give this a shot. I have tried two USB flash drives, both FAT32 using these commands:

diskpart
listdisk
select diskn (where n is the number of the pendrive)
clean
convert mbr
create partition primary
select partition 1
active
format fs=fat32 quick
assign
exit

Yes, the USB flash drive was put into the white slot. I held down the button for three seconds, the button and my flash drive would blink for a minute, then the button would remain a solid blue which i read means it's okay to boot (asus sabertooth manual didn't state otherwise).

When booting, I get the solid CPU_LED light on the mobo, and nothing else. no post, no beeps, nothing. I've tried one dimm, two, no dimms, no card, hell I don't even get a warning beep for not having a GPU or memory, just solid CPU_LED and that's it. I've tried pulling the battery several times. I believe it's fooked now.

@d4nt3ch - You mentioned bricked BIOS, yet carried on with diskpart? What are you doing there, formatting a USB with Diskpart?? If yes, that is odd, stop it and use windows right click format J/K but not really, no need to use diskpart

All BIOS here are tested, except the BIOS at #189 so any bricked BIOS would be random fluke. And, that BIOS is waiting on test report back by user that requested it, so you shouldn't be using that without discussing first?
So, which BIOS are you talking about here, what post? As mentioned, all already tested and working except the one at #189, and on that one I warned user it shouldn't be made with the source he gave me, so if it bricks his too we'll soon know.

YOu have USB Flashback, so nothing to worry about, unless something else on your board happened to die/fry at that exact reboot moment. (I've seen it happen, it's called "my luck", lots of people have this issue )
Rename stock BIOS to USB Flashback name, put it on USB, use flashback = problem solved, unless there is some other physical issue with your board or CPU etc.

I used diskpart suggested from another forum with a user with similar issues. I did also try right clicking, format via Windows or disk manager, got the same result.

I tried flashing 4709 bios, renamed to flashback name (saberx79.cap) the result is the same, solid cpu_led and nothing else.

I tried your bios from post #1 which is v4.

Is the flashback button blinking for a minute, then going solid blue normal? Once it goes solid blue it never turns off.

I just thought it was funny and far to involved to format a USB stick, it's OK to do, but not necessary. Sounds like your USB is not compatible, that is the issue here.
You need USB 2.0, older/smaller/cheaper = best, 128MB-2GB ideal. If you have new/large one, format to 1GB and try again. BIOS on root of USB, not in folder

BIOS in post #1 is not mine, and I don;t know anything about it, you'd have to wait on reply from @agentx007
Since it's a BIOS from 2017, it may just not be compatible with your CPU, which the latest BIOS flashed by flashback should re-correct the BIOS and let it work withyour CPU again, so some issue at flashback I guess.
Ahh, you said 1709, try latest stock BIOS renamed and try again! That would be 4701 or 4801

It should flash for a while, getting faster and faster, but then I can't remember on X79 if it goes off or stays on for being done/normal and working. When it's not working, I'm pretty sure it always flashes once or twice and then shuts off, or it may stay solid, but it doesn't flash for a long time when it's not working.

I did place cap file in root dir. I also did try latest stock bios from Asus website, no luck.

Can you link me your latest bios? I'll try that. I'll also try converting the USB stick to 1gb fat16.

You need to use stock BIOS right now, since you cannot boot, nothing else matters until you fix the board. And for that, you now need to find a compatible USB stick.
Don't use FAT16, use FAT32, and yes try formatting down to 1GB. Must be a USB 2.0 stick too