I have this card in PCIe x16 on a HP Proliant ML30 Gen 9, it has an embedded Matrox Ge200h which is the only working display. It is strange that while it is booting I can see UEFI logo and Ubuntu logo on every monitor but after automatic login only the matrox display is available. No signal is sent to the other. So I cannot expand desktop through the monitors.
Embedded and PCIe display are enabled in bios, tried to enable only pcie and both displays attached to it are disabled after auto login. Tried to install amd proprietary driver but is an old card which is not supported. Tried to add kernel parameters amdgpu.rc=1 amdgpu.noretry=0, even radeon.disp_priority=2 but nothing. Even tried to boot with old kernel (5.11) and nothing. Did a dmesg and amdgpu and radeon modules are loaded without any issues included the ge200h module; but DVI and DP ports are not reported by xrandr, just the embedded VGA.
I tried Mint 21, Manjaro 21 and the same happens. By the way I have attached DP to HDMI and DVI to VGA adapters which are the only issue that can explain this. Windows 11 detects it correctly, I doubt they are the problem.
Hope you can point me in right direction, thanks in advance.
