Solution to plug more than 4 GPUs in a Prime Z390-A or Prime Z390-P motherboard

[Didz]

I spent almost a week trying to figure out why I was not able to plug more than 4 GPUs on my mining rig using HiveOS. I couldn't found solution for my issue anywhere so I thought why not sharing it on Bitcointalk to help other GPU miners.

So I have these 6 GPUS:

5 X ASUS Dual GeForce GTX 1660 SUPER OC Edition
1 X EVGA GeForce GTX 1660 SUPER SC ULTRA GAMING

I first tried to fix my issue by plugging each GPU directly on my Prime Z390-P motherboard but because the PCIe x16 slot was not reinforced I broke it.

I bought another motherboard, this time the Prime Z390-A.

After countless trials and errors what finally fix my issue was to set these settings in the BIOS:

- PCIe Speed : Gen2 (for all the PCIe slots)
- 4G Decoding : Enabled
- CSM Support : Disabled

I hope this post might be helpful for someone stuck with the same problem.