I have tried searching through a lot of the threads in this forum but haven’t found something directly relating to adding bifurcation support to a NON-UEFI BIOS. I followed the guide to extract and use a hex editor to analyze the different ROM modules but am unsure if this is even what I need to be modifying to configure bifurcation support on an ASUS P6T7 WS SuperComputer.
I read through a few guides on UEFI BIOS’ for X79 and X99 and the interface had references to PCIe slots and the configuration to run them in. Am I missing a tool or has anyone gone down this path on a non-UEFI BIOS?
[Guide] - How to Bifurcate a PCI-E slot
And this is from Intels own X58 specsheet;
3.2.2.1
Port Bifurcation
The IOH supports port bifurcation using PEWIDTH[5:0] hardware straps. The IOH supports the following configuration modes:
• The width of all links are exactly specified by the straps
• The width of all links are programmed by the BIOS using the PCIE_PRTx_BIF_CTRL register (wait on BIOS mode
I have a BIOS file, opened it with MMTool3.26 and have HxD hex editor installed at this point.
This BIOS/Chipset is too old for that kind of edit/controls etc. It’s nothing to do with UEFI/Non-UEFI BIOS either, it’s just too old of a system, CPU, board and BIOS does not have these kind of controls
This was not a thing back then, at least not for end users, nor have I ever seen even hidden in BIOS - maybe odd/random X58 server BIOS could have, but I’ve never seen
Here is your reason to upgrade, now is the time 
Really appreciate the quick feedback. I did find an old X58 SuperMicro server that apparently supports the feature in it’s BIOS for the 1 PCIe slot it has…
SuperMicro X8DTT Series:
IOH PCIE Port1 Bifurcation
This feature allows the user to set IOH Bifurcation configuration for the PCI-E Port
1. The options are X4X4X4X4, X4X4X8, X8X4X4, X8X8, and X16.
I’ll do any legwork if you can point me in the right direction and you think this could be a potential reference for configuring bifurcation on specific slots in other X58 motherboards.
https://www.supermicro.com/en/search?Search=X8DTT
Also, this is more of a fun concept rather than something I’m relying on. My main system is actually using an ASUS X79-Deluxe so maybe I’m better off trying to get bifurcation enabled on that board later down the road when I updgrade and switch over my server off of the X58.
You’re welcome! Then you need that Supermicro board 
Nothing can be done on other board BIOS, unless similar settings are already there hidden in the BIOS, which it’s not for your board I checked before I replied.
Yes, you can use bifurcation on Asus X79, and I’ve already modified plenty of those variants to allow user access to the relevant settings in the BIOS for all those models too
Here is NVME Mod + Bifurcation enabled menu mod 4801 BIOS for P9X79 Deluxe - [OFFER] ASUS P9X79 DELUXE BIOS 4801 MOD NVME Dxe4 (2)
Understood - At least now I can stop considering bifurcation on X58.
That’s a different BIOS than what I have for the X79 Deluxe, correct? Appears ASUS labeled this BIOS 4805;
https://www.asus.com/us/Motherboards/X79…/HelpDesk_BIOS/
I’ll save that page and revisit for the future move.
At least for your X58 board it’s not possible unless you get Asus to make you a new BIOS. Plug in something with two cards in one adapter into each slot, you may find one of the slots already bifurcated by default.
Yes, that is older BIOS I linked, hadn’t see 4805 until you mentioned. When you are ready, I can make you new mod with the 4805 BIOS When you do want it, post in that thread, so I can make new one and post there for others to use in future too
Actually, that’s a different model altogether, sorry, I forgot they had Z79-Deluxe and P9X79-Deluxe back then. I would need to make you BIOS anyway, all those I’ve done are for the P9X79 board variants.
* Edit - I checked, and that model does have bifurcation controls hidden from you in BIOS, so we can do mod
Well then I’ll create a new thread in the very near future. Thank you for the knowledge! I will definitely end up trying out a few PCIe slots on the P6T7 WS Supercomputer, the fun part about that board is the 32 extra PCIe lanes from two NF200 chips on top of the chipset. We’re talking a potential 12+ more NVMe SSD’s alongside a GPU installed running at x16. While it’s PCIe 2.0, the idea is with more size-oriented SSDs coming out using QLC nand the prices should come down a bit as capacities increase.
You’re welcome! Yes, sorry, I forgot they had blue and gold versions of X79, I can’t believe no one with the gold boards have asked for these mods previously!
Yes, it would be nice to get bifurcation on at least some of those slots on the P6T7, and you may find one or two split, but without it being a hidden or visible BIOS setting I can’t tell how it is by default for this board (maybe some done already, maybe none, only you can check and see)