[Request] Enabling PCI-E bifurcation on ASRock X99 Extreme4

[Pentium320]

Hi, and welcome to forum!

So, I need to enable bifurcation on my ASRock X99 Extreme4 for PCI-E to use more than one NVMe drive in my PCI-E adapter, that has 4 slots for NVMe drives. No such option in BIOS, and by default - as expected - only first drive is detected. Using Xeon E5-2697 v3 CPU, so PCI-E lanes shouldn't be a problem.

My current configuration is: GPU in first PCI-E slot, and NVMe adapter in third slot - and want to set bifurcation on that 3rd slot.

Tried to do it by myself with AMIBCP > IntelRCSetup > IIO 0 (tried on other IIO's aswell), and setting IOU1 (tried also IOU0) to x4x4x4x4 mode, as in the screenshot. But, uhm - it doesn't work, other drives than first still not visible. 

Attaching BIOS dump, done with AFUDOS (FPT actually doesn't want to work with this motherboard). It's based on 3.60 version.
Just as a notice, this BIOS is already modded with Turbo Unlock and CPU undervolting mod - don't want to lose those

Not really sure what I'm doing wrong, but options, solutions or ready-to-go BIOSes are welcome.
Thanks in advance for help!

[Odenrir]

I checked the specs of the ASRock X99 Extreme4, and it looks like the 3rd PCIE is x4 2.0, so what you want to do it is impossible. PCIE1 and PCIE2 are X16 3.0, so you can bifurcate 1st or 2nd slot through bios mod. I have done this in the past with the asus sabertooth x99 in the second X16 slot, the only bug I see is that bios only shows the first nvme but once system starts every nvme is detected, also in the boot menu every nvme is shown.