[So close to success] x99-ud4 5820k x290+5770 Sierra boot

Apr 27, 2011
GA-X99-UD4 F22
GTX 1070 Ti
So everybody knows that the x290 is "unsupported" card now - the PC must have a secondary GPU (several tutorial with iGPU are available) to have any chance to boot with Sierra.
Unfortunately x99-ud4 have issues with more than one GPU and the 5820k goes not have iGPU (and the board also does not have connectors for iGPU) so after "several days in restless fight" I finally succeeded to install second GPU (ATI 5770 - a very well supported GPU by Apple) in my x99-ud4.
The trick is to update the BIOS to F22, use a "extra efi file" (Test2-2016.efi - and using the latest Clover with AptioFix2Drv I successfully passed the malloc step (you may have to do a CMOS reset to clear the BIOS memmap)

So having x99-ud4 F22 I installed and booted 10.11.6 - it works perfect.
Now the attempt to do Sierra boot is so close....
I Installed Sierra on another partition (so I can safe boot back to 10.11.6) and I was hit by boot issue (the install was OK - I failed on the final step - boot after the install.

If I have only x290 clover boots, after several screen of console dump (indicating that all is fine) it power down all outputs of the GPU - and that (the PC works with no signal to the display)

If I have only 5770 sierra boots fine - I complete the install log-in "all is working"

Now the tricky part - I want to keep both cards "attached" to the PC (I have W10 so 290x is "must have")
When both card are installed (no matter which one is in PCI-1 or PCI-2 and it does not matter in BIOS which PCIe slot is marked as Primary) I can not pass the boot part (will attach picture is someone is willing to help)...

Now I need some help - how I can "disable" the 290x with Clover so the Sierra does not "find it" and does not stuck during boot. I was thinking about some SSDT or Injection patch so the Clover announce the 290x deviceId as "unsupported" by Sierra (because I think Sierra see my card and attempts to init it but with no success). So if I some how "soft disable" the 290x and keep only 5770 visible to Sierra then I should (I hope) to boot (I confirmed that the Sierra boots 100% safe if the 290x is "unplugged" from the MB.

So any help or advice is welcome