Add PCIe bifurcation to ASUS P8Z77-V?

Hello, new member here looking for help. I recently bought an “ASUS HYPER M.2 X16 CARD V2” expansion card and I was able to mod my ASUS P8Z77-V BIOS to add NVMe boot support, so far so good. But I when I added a 2nd NVMe to the expansion card, the BIOS would only show the speed of the slot and the first NVMe, and Windows 10 would not recognize the 2nd stick at all in Device Manager. If I added that 2nd stick to my old “ASUS HYPER M.2 X4 MINI” expansion card (that I bought but never installed previously), Windows recognizes it fine. But I’ve ordered a GPU to put in PCIe_1, and when I add a card to PCIe_2, both _1 & _2 will be at x8. If I put the 2nd NVMe expansion card in the black PCIe_3 slot, that storage performance will be severely hampered. Attached is the current BIOS I’m using.

I’ve inferred from other sites that the problem is due to a lack of proper bifurcation support on my motherboard? I’ve also read that a carrier card with a built-in bridge would fix this issue, but I’ve not been able to find one that is also bootable. I guess I could buy a 4TB NVMe, but I’m hoping there is a solution to mod the BIOS to allow what I’ve already purchased to be recognized by Windows in PCIe_2.

I also found this repository, but it’s not clear to me if any of the mods there include bifurcation support.

Thank you for any guidance you can offer.

Z77VB.rar (4.02 MB)

@evc69 - Hey, welcome to the site!

This board/BIOS is too old for Bifrucation, only Asus could add or adjust that. There may be some slot that is bifurcated by default, but I doubt it. Test all slots one by one with two NVME in the Hyper card, including the main PCIE x16 slot you’d normally use GFX card in
Also, see here, my comments and testing with Hyper V2 card - [REQUEST] Bifurcation Asus x99-a II - 5820k (2)

Thank you for the quick reply! That’s disappointing. I’ll look into riser boards with a bridge built in. Where can I find details on the available BIOS patches and/or additional modules that can be added to my BIOS? Is there a readme that details the changes in the updates?

@evc69 U wont get PCIe bifurcation on that board, instead u should have picked a NVMe adaptor with a chip bifurcation as u can see in the P8Z77 Deluxe/Premium or Maximus V Formula/Extreme, not the V.
Off course a lot more expensive that the Hyper M.2 from Asus.
Also this operation and resources available, will depend of the PCIE lanes available in the motherboard.
Modules/patches to add to ur bios…dont think so…and never saw it done for what u intend.

@evc69 - You’re welcome! Sorry it’s not good news
Time for new modern board Or get an older X79 or X99 or X299, some X58’s you can do it on too but if you consider those as someone to look in BIOS for you first.

I think the only PCIE Cards like you want with built in bifurcation are $200-300 or above, examples below…r/dp/B07HYZY7P2…/dp/B073W71K4Z/

As for adding stuff in your BIOS, I assume you mean update modules? If yes, we have several sections here in the forum, for modules such as RAID or other option roms like LAN/Audio etc, and ME FW has it’s own section.
Change logs, I doubt you will ever find that for anything, maybe a RealTek LAN module if you can find on their site, but it would be rare