@Nitrako - That's probably due to ME FW corrupted. I think you already solved this as mentioned in PM, but if @chi needs to check, look at BIOS main page and see if you see ME FW shown, if not check with HWINFO64 in the motherboard section. If you see N/A or 0.0.0.0 this is corrupted ME FW

@Lost_N_BIOS
No, after i flash SABERX79.cap via flashback,
ME Firmware from "N/A" goes to "8.1......"
but still ram wont go over 1333mhz.
Ram is 1866mhz btw!!

UPDATE1: Problem might solved when i flash bios from post #147 via flashback.
(SABERTOOTH-X79-4701-uCodes-NVME-10-13-2019.7z)
which means that problem is not occured by ucode updates or NMVE( if ucode from bios #134 is as correctly as the one from #147).
So propably something going wrong with (+bifurcation mod et all) or (updated RST/RSTe as presented in stock BIOS layout, updated Marvell) from post #134

UPDATE2: i flash bios from post #33(in this thread [GUIDE] Adding Bifurcation Support to ASUS X79 UEFI BIOS (3))
(Saber-X79-4701-uCode-NVME-PCISub-SystemAgentSwitch.7z)
again everything looks ok, so the problem with ram frequence doesnt come from Bifurcation mod(if bifurcation mod in bios from post#134 is as correctly as the one from post #33(in this thread [GUIDE] Adding Bifurcation Support to ASUS X79 UEFI BIOS (3)) .

UPDATE3: i flash again bios from post#134 but again memory frequency can't go over 1333mhz..
Also CPU VSSCA VOLTAGE CAN'T go over 0.925 as its set manual in 1.200v(manual offset)..i say again this problem solved if you flash bios from post #147 or bios from post #33(in this thread [GUIDE] Adding Bifurcation Support to ASUS X79 UEFI BIOS (3))

@Lost_N_BIOS
Can u make two Bios to test what is the problem:
1)Take the bios from post #147(in this thread [OFFER] ASUS Sabertooth X79 4801 beta BIOS (compl. updated incl. NVMe support [v4]) (10)) and add bifurcation mod et all
2)Take the bios from post #147(in this thread [OFFER] ASUS Sabertooth X79 4801 beta BIOS (compl. updated incl. NVMe support [v4]) (10)) and add (updated RST/RSTe as presented in stock BIOS layout, updated Marvell) like you did in bios from post #134( in the same thread as previous)

All is fine, it's due to what you did at first attempt with fixed BIOS I sent you >> -rewrite option at entire BIOS, I forgot to put -bios flag in command I sent you.
Previous mod BIOS is fine, tested by several users, all issues you ran into due to what we did for your system only. Stop using -rewrite, that only for certain situations, and limited usage (Just saying now, in case you keep using it)
BIOS at 147 may be issue, but I doubt it. However, do not use that to flash entire BIOS or ME, nor use that BIOS ever with FPT, this is a stock BIOS, USB Flashback ONLY ALWAYS. If you flashed this EVER with FPT, then you lost your NVRAM, serial, UUID etc again.

I forgot to ask too >> when you enable XMP, did you also change memory speed to whatever you want? if not, do that now, does it still remain at 1333, if yes, probably ME FW issue, unsure, need to see MEInfo report from you still.

@Lost_N_BIOS
i will post here again Asus Saberx79 Modded bios 4701 request for all others who are interested about those mods:
1)NVME to latest
2)Ucodes to latest
3)Bifurcation with all hidden controls(+ PCISub, SystemAgentSwitch,) and fully unlocked bios
4)Update iRST (w/RAID TRIM), RSTe (Update to any "safe" version you want)
5)Update LAN
6)Update Marvell

@Ntrako w/ 4701 BIOS?

yes i have corrected it..bios version 4701

@Ntrako - Please test this BIOS first (via USB Flashback) - this was my starting base for recent mods here, if there is some issue remaining it could be carried from that and no one reported issue on that BIOS
[GUIDE] Adding Bifurcation Support to ASUS X79 UEFI BIOS (3)

I have already test it(you can see my post #152 ,Update2)
At least there is no issue with ram frequence

OK, thank you for confirming that one is OK! Next, I will update ONLY microcodes to latest, before doing rest, that way we can rule out any microcode related bug, since we know ME FW is OK, yet memory/XMP is messing up.
Please wait, sorry I can't do this now, will do it first thing tonight when I get back.

* Edit - @Ntrako - here is that initial test for you, rest I will do tonight. This is BIOS mentioned above + all ucodes updated only

Flash only by USB Flashback

I dont have any issues.
Everything is good right now with VCCSA Voltage and ram frequence
you can continue ;)

@Ntrako - Thanks, here is next two tests, if all OK here, I will combine all these into one final BIOS (without any Marvell update) If you want Marvell update after that, do by UBU

Those files are .bin. How to flash via flashback?

Yes, sorry about that, sent encapsulated links in PM

here i have the results mate:
1)when i flash the one from LAN everything is good
2)when i flash the RST the problem occur again..so the issue with cpu vccsa voltage and ram frequence come from RST

Thanks, uCode-LAN is new base for a minute. Here, please test all three, let me know which causes the issue again (if possible don't boot to windows for these tests, due to some will have new some old RST roms and that may mess with the drivers you have installed)
Actually, I bet it's the orom, and either how it's put in, or the rom itself. Lets test this, first, here is orom RST only edit, done as I sent you previously, but without the RST EFI modules updated.
If this fails/causes the issue, I will send you three more to test of same orom version change, but using different tools and or different version of the tool for the edit

* Edit - @Ntrako - Getting ahead here, next three using different versions/tools/methods

If all these fail, cause the issue, then something with one of the oroms below is issue, which we'll further narrow down until we find the cause
OROM IRST RAID for SATA - 12.7.0.1936 >> Update to >> 13.1.0.2126 TRIM mod
OROM IRSTe RAID for SATA - 3.5.0.1005 >> Update to >> 3.8.0.1029