No post for external GPU using slimsas

[sappireflames00]

Hello, I have a dl385 gen 10 plus server., It is functional for the most part. However I am trying to install an external gpu (because the gpu is physically too big for the server) using a PCIE x16 to slimsas. tot then a slimsas riser. I've tested another GPU in the PCIE slot as normal and in this case the server recognizes the card normally. However once I try to use slimsas, nothing ever shows. The server doesn't pick up the riser or anything., I have tried multiple risers, cables, nothing. A while back I tried the same setup on a consumer board, a b550 I think, and it worked. So I'm a little confused, does anyone know if there is a bios setting or something? Maybe an OS setting? I am using proxmox 8.4.0, but like I said, the other card I tried was registered just fine.  Any help would be greatly appreciated. Thanks.