mining pc PC Won't Post When Adding GPUs

[PrematureCorn]

Hi everyone, 

I am upgrading my mining rig to 8 GPUs and I am currently able to get the system to post with 4 GPUs but not 6 or 8. I am running two power supplies for this build and I would like to run 4 GPUs on each PSU. I believe I have wired the power supplies correctly since the system works fine when I run 2 GPUs off one PSU and 2 off the other PSU. I originally thought maybe not enough power was being supplied by PSUs so I ran all 4 GPUs off one power supply and the system still posted and ran fine.  

 

I have also upgraded the motherboard BIOS to the most recent version but I still can't get it to post with 8 GPUs. Does anyone have any advice for what could be happening? 

 

Here is the full parts list of my build:

(1) CPU.... Ryzen 5 5600G, 6-Core 12-Thread w/ Onboard Graphics

(1) Motherboard.... ASUS ROG Strix B550-A Gaming (Includes PCIe 4.0, 2.5Gb LAN, BIOS Flash, etc.)

(1) Memory.... TeamGroup 16GB DDR4, 3600MHz CL18 (2x8GB, Dark Color)

(2) Power Supply.... EVGA SuperNOVA 1300W, 80+ Gold, ATX

(1) SSD/Storage.... Kingston 240GB A400 SATA3 SSD

(2) PCIe Adapter.... XT-XINTE PCIe 1 to 4 PCI-Express 16x Slots Riser Card, PCI-E 1X to External 4 PCI-e USB 3.0 Adapter Multiplier Card for Mining

(8) Risers.... VER009S PCI-E Riser Card

 

Graphic's Cards:

(1) EVGA GTX 1080 Ti.... Black Edition

(1) MSI GTX 1080 Ti.... Gaming X

(2) EVGA GTX 1080.... Hybrid AIO

(1) EVGA GTX 1080.... Founder's Edition

(2) ZOTAC GTX 1080.... Amp Edition

(1) EVGA GTX 1080.... FTW

 

[ZROCK]

First off fuck you for mining. Second, just build a different system for 4 more gpus. Run two systems. Cramming 8 gpus into a single motherboard is like trying to cram a cheerleader full of 8 different dicks