so i got it working right now with Rom Bar / PCI Express / Primary GPU off
my config is :
agent: 1
bios: ovmf
boot: order=ide0;ide2;net0
cores: 16
cpu: x86-64-v2-AES
efidisk0: local:300/vm-300-disk-0.raw,efitype=4m,pre-enrolled-keys=1,size=528K
hostpci0: 0000:0a:00.5,mdev=nvidia-527,rombar=0...