Question Linux won't post with (amd 340x) gpu in the pcie slot. (MacMini running Linux)

[FlashStopFall]

I'm running Ubuntu 22 on an intel Core 2 Duo MacMini. It's a 64-bit OS, but the EFI is 32-bit. The motherboard uses a fully featured mini-pcie slot for its network card, which has proven to be able to work with various pcie devices via an x16 riser, but it appears that testing gpu's on this slot never really happened due to mini-pcie to x16 riser limitations circa 2007.

I have a mini-pcie to x16 powered riser plugged into the machine (therefore limited to x1 lane and pcie gen1 here). With the AMD 340x gpu plugged into the riser, the machine won't POST. The CPU fan kicks in on low like it normally does, and the gpu fan comes on at the same time (also on low, not full blast), but nothing else happens, and it never gets to the magical mac POST chime. This happens with or without amdgpu drivers installed. I've also tried setting amdgpu.pcie_lane_cap=1, pcie_gen_cap=1, and pcie_gen2=0. If I plug an HD7870 into the riser the system boots normally but the GPU does nothing, I think this is because I didn't provide any external power to it though. I'll have an AMD HD6350 to test soon too.

Is it possible this GPU is dead? What would cause it not to reach POST? Since other cards have been used with this slot, I would think I could at very least detect it in the system.

Edit: I just got power to the HD7870 and while the machine booted this time, it didn’t see or detect the gpu at all.

 

[white.a.drew]

I'm running Ubuntu 22 on an intel Core 2 Duo MacMini. It's a 64-bit OS, but the EFI is 32-bit. The motherboard uses a fully featured mini-pcie slot for its network card, which has proven to be able to work with various pcie devices via an x16 riser, but it appears that testing gpu's on this slot never really happened due to mini-pcie to x16 riser limitations circa 2007.

I have a mini-pcie to x16 powered riser plugged into the machine (therefore limited to x1 lane and pcie gen1 here). With the AMD 340x gpu plugged into the riser, the machine won't POST. The CPU fan kicks in on low like it normally does, and the gpu fan comes on at the same time (also on low, not full blast), but nothing else happens, and it never gets to the magical mac POST chime. This happens with or without amdgpu drivers installed. I've also tried setting amdgpu.pcie_lane_cap=1, pcie_gen_cap=1, and pcie_gen2=0. If I plug an HD7870 into the riser the system boots normally but the GPU does nothing, I think this is because I didn't provide any external power to it though. I'll have an AMD HD6350 to test soon too.

Is it possible this GPU is dead? What would cause it not to reach POST? Since other cards have been used with this slot, I would think I could at very least detect it in the system.

It is most likely the card being dead. If you can test I. Another machine would help. But seeing as other cards have no problems I would see the card being dead a high possibility