Taichi x399 and more than 5 gpus

Hello , i am trying to lunch my system on more than 5 gpu
My build is :
CPU : Threadripper 1920X 12 cores 3.50 GHz
RAM : 8 x 16 GB Gskill 3200. (128 gb total)
GPU : 7 x GTX 1080 TI 11 GB
PSU : 3 x Corsair HX1200i .
BIOS version : 3.60

I am using PCI-Express card model : EUX1-04 to convert 16x PCIe to 4 1x PCIe to able to connect all my gpus.

1 gpu is connected directly to PCIe x 16 slot (Slot 1at the top of motherboard)

No i can post and lunch system only with 5 gpus . And it's working perfectly. (BTW It's not mining , i am building for rendering)

When i am connecting 6 gpus , bios is not posting , it's going in a rebooting loop . And its rebooting at the end of post code list something around 92 - 99 coz after that screen with Asrock logo should appear.
After some bios tweking , disabling hardware i don't need in bios i managed to post and Windows 10 64 bit is loaded ! But still it see only 5 gpus. :(
I was looking forums and founded that enabling function called "above 4g decoding" could help , but unfortunately i can't find it in bios . Can some one help me ?

Hi

Would you be so kind to elaborate on your set a bit more, if possible some pictures would be great!

thanks
mano

Did you ever solve this? I'm trying to do have 6-8 cards too and also getting stuck on 5 cards. I found above 4g decoding, but it isn't helping.