This one, along w/ vcore please check >> Advanced >> PCI Subsystem Settings << Do you see that menu now (contents irrelevant ATM)
http://s000.tinyupload.com/index.php?fil…133354011469173
UEFITPCISub BIOS
vCore = Good
PCI Subsystem Settings = Good (can see the menu and contents)
@Xenophobian - Great, moving forward, here is two BIOS, both adding new System Agent menu in different ways. Please confirm both have (only) the new System Agent (other contents irrelevant for now), without VT-d at top, and do your vcore check.
http://s000.tinyupload.com/index.php?fil…938512323197101
I assume the vcore issue may come from one of these edits, SASwitch is original method I use on all other Asus X79 edits please test first, SASwap is swap method not generally used because it’s an unnecessary edit method (ie more bytes changed overall).
I’m running into issues with another less common Asus X79 too (P9X79-WS-IMPI), maybe both your board and that one need this less common edit instead, possibly due to different BIOS engineers making these or something?
All other P9X79 variants have been fine with normal method to do this unlock, I done probably 10+ different versions across the many variants and BIOS versions.
Do I just rename the .bin files to .CAP or is there something else I need to do to use these?
@Xenophobian - Ahh, sorry about that! I forgot to put back into capsule for you, please wait, I will edit into this post in a few seconds.
http://s000.tinyupload.com/index.php?fil…215161389770578
The Motherboard wouldn’t finish posting and kept boot-cycling when using the “SASwitch” BIOS. Tried flashing it two different times to make sure.
When booting into the “SASwap” BIOS there was no vCore issue but System Agent section only showed this;
http://v-rlaw.com/carni/images/overclock…oddedBIOS-8.jpg
@Xenophobian - Hmm, that is odd @ SASwitch! That is original method I always use, must have been some glitch/error on my end when I did the edit I will check. Could you enter BIOS?
SASWap, odd as well, that is original SA Menu in your image, should be new one 
So odd all these issues with such a simple edit I’ve done a million times now 
Please test, 2 x new SASwitch - http://s000.tinyupload.com/index.php?fil…820596070187114
If both those have the vCore issue then we know it’s this, and I will go back and redo SASwap and hide the default menu and move forward on that.
So I tried both versions in the new file;
BCP - no vCore issue, modded SA menu is present
Man - Boot loop, had to use BIOS flashback
@Xenophobian - Thanks, very strange, both those files are same/same, just recompiled in different ways. Seems for the SA switch rebase needs done by AMIBCP for this model, instead of manual insert of same exact edit (I can’t see any reason for this, post recompile each module is exact same?)
Random anomaly I guess!? Works fine on other variants to do manually, and it’s best to do that way so no rebase of the entire volume, but at least now we know, thank you for all your testing!
One more test needed I think, then we can wrap it up and unlock it all again. On new System Agent page at root, you can’t see “Spare Err Threshold” setting, correct?
I assume not, and that will be target of next test, but let me know first before I do anything, that way if you can see it we’ll need to pick something else instead (inside IOH)
Correct, “Spare Err Threshold” setting is not in the root SA menu. Is there somewhere I can find out what all these fancy new menu items actually do? Aside from configuring bifurcation, I know what that’s about 
@Xenophobian - Just google 
Here, please test both of these, let me know which shows you Spare Err Threshold at root of SA, and if either have the vcore issue.
I think this last test, once results are in I will unlock all rest I normally do for this mod. - http://s000.tinyupload.com/index.php?fil…919628042173796
I think the issue happened oddly due to not using AMIBCP to hide that menu at the switch point vs doing it manually (Usually manually same, and best due to less other changes made in BIOS rebuild)
I think probably same reason I had a similar bug creep in with Chassis Intrusion for the P9X79–IMPI users I’ve been working on unlocking Ai Tweaker menu for recently. We’re doing step by step test there too
Haha, Google it is. Just wanted to ask in case there was already a thread on here from your other ASUS X79 mods that covered a lot of it.
BIOS S : No vCore issue and Spare Err Threshold appears
BIOS U : No vCore issue and Spare Err Threshold appears
Both of these versions worked fine.
Yes, google is how I learn when I don’t know Some stuff I may be able to answer you about, but Spare Err is certainly not one of those things I know about
I only picked that setting because I know from other Asus X79 BIOS variant edits that this setting was the sole setting on that page that needed access level change to become visible, which you tested above and seems either works in this case and neither caues the vcore issue (so final test now done!)
I will make a final complete edit shortly and then repack a release package and kill all links in this thread except that one, so only the good final BIOS will be here for others
Thank you for your time testing this out with me, and thanks for putting up with all the actual testing!
You’ve helped me see a reason for possible cause of issues on other variants of Asus X79 with bifurcation edit too, hopefully what we learned here will solve that issue too
We’re currently having a Chassis Intrusion issue on P9X79-WS-IMPI when same edit was applied, now I thikn/hope I know why from your testing - So thank you! 
@Xenophobian _ final test, this is final BIOS, but not in a repack with change log or proper name folder etc. Once you confirm all is OK, I will do repack and remove all test BIOS links here
http://s000.tinyupload.com/index.php?fil…810027614862095
*** Updated version here at post #83, adding latest CPU microcodes as of 11/25-2020 (above contains stock microcodes) ***
Nice work here, I may be able to do some testing this weekend. Had been thinking of grabbing one of those Hyper M.2 cards which needs bifurcation as I picked up a couple of 2tb 660p’s recently on sale.
@tbob22 - all testing may be done, and I will repack a final ready BIOS shortly
I wonder why we don’t see more often, the supermicro bifurcation card being used or discussed (AOC-SLG3-2M2)? It’s about $20 cheaper ($38 on Amazon), but maybe people don’t know about it, or they just think it only works on Supermicro boards?
Good point, but that only has two m.2 slots right? The hyper has four which would make full use of a 16x slot. I think ASrock has one as well but it’s much more expensive.
Yes! I didn’t notice the Hyper had four slots, I always thought it was two slots 
Well, I guess that one is best choice then unless you want to spend $100-150+
But, if you’re only using two NVME’s, I’d get the cheaper Supermicro one
Yep, I’m currently using two of the smaller single slot hypers for my 960 and pm963, they were about $10 each used. Would be nice to have all of them in one slot along with the new 660’s :).
Single slot, how is that “Hyper” I use a $4 card for single NVME, works fine - https://www.amazon.com/gp/product/B07GPBBCGS
Since you only have two NVME, maybe you should try the Supermicro I mentioned, and then you can start the new discussion about it and get everyone hyped up about it
I did see those cheap ones before but the reviews (at the time) were mixed, so I figured an Asus adapter may be a bit better quality, so far so good about 3 years later. Maybe the cheap ones are better quality now, but that 960 was pretty expensive back then so I went a bit safer. The pm963 is also 110mm so it wouldn’t fit on some of those smaller ones.
I have four M.2’s, the two older ones in the board now and the new 2tb 660’s. 