That's what also happens to me, if i put both cards in my i5 4590t system they work without problems.
Hi, i was trying to add another SATA PCIe card to my home server running proxmox, so i decided to buy another of those cheap ASM106x card, from aliexpress this time instead of amazon:
but as i try to boot i get some strange behavour: some time it get stuck on this screen, trying to find all the hdd connected (7 in total), sometimes it get stuck on the boot logo, one time i get it to boot into proxmox but the ethernet port of the motherboard wouldn't work. I'm running a ryzen 7 1800x with a Gigabyte ga-ab350m-ds3h motherboard and a gt710 as a video output. If i put only the amazon one it boots with or without disk connected, if i put only the aliexpress one it boots only without disk attached, and i've tryed swapping pcie slots and even removing the 710 but nothing changes. I don't know if i have something to do with the firmware or if i did get just a faulty pcie card. Plz helb.
https://preview.redd.it/scmg4cmx47zb1.jpg?width=4624&format=pjpg&auto=webp&s=2705398cf257d3e135a70ac9daf0403091ef6cc2