Already posted to r/homelab and r/vfio, but got no replies. It's a gigabyte board, so maybe somebody here can help.

I'm currently in the process of upgrading my homeserver. I have four pcie cards I'd like to use:

• Two Intel i350-t4's
• A LSI 9300-8i, which is actually an IT-Mode flashed, known-to-work Fujitsu CP400i
• One GT710

No matter the order I plug them in, I cannot get all of them to work at the same time. I can run the GT710 and the two Intel cards just fine but when I plug in the 9300, one of the Intel cards just disappears from the bios, as if not plugged in. The 9300 itself doesn't show up, either.

I've tried pretty much every combination, I've tried manually setting bifurcation to 8/4/4 and installing the cards in that order, I've tried setting everything to PCIe 3.0, CSM, no CSM, ... Same result. The LSI card is confirmed working in another system (Z590 Vision D, i5 11500) and from what I've read so far, this shouldn't be an issue. Am I missing something? I wonder if it's power-related, since not even the LED is turning on. When installed on the Z590, it lights up immediately. PSU is a 550w be quiet! Straight Power Platinum.

I also tested an old Dell H200, which is PCIe 2.0 whereas the 9300-8i is 3.0. The H200 works, gpu, dual nics and all.