When adding 5th GPU, Hive will not boot. Screen is scrambled and no POST

[jc_hive]

Hi all, when adding a 5th GPU to my rig, I run into an issue where it will not boot. There is no POST screen, instead I am greeted with scrambled RGB colors.

I’ve tried swaping out cards, risers, added/removed PSUs (5 different ones). Changed the 1x card, changed the 6-8pin cables and tried moving the cards to different PCIe ports on the motherboard. Any time I hit the 5th GPU, the whole thing scrambles.

Here is what the screen looks like when it tries to boot:

[Album] imgur.com

Any ideas out there?

Edit for hardware:
Motherboard
PRIME Z390-P ASUSTeK COMPUTER INC. (2804 04/15/2020)

CPU
6 × Intel® Core™ i5-9400 CPU @ 2.90GHz AES

Disk Model
SPCC M.2 PCIe SSD 256GB

RAM:
8GB DDR4

Edit: Also updated to the latest BIOS, tried to disable as many PCIe things I could think of like the SATA ports. No luck yet.

[jc_hive]

Solved this after settings PCIe to Gen 1 in two places in the BIOS.