Note For NVIDIA Blackwell (GeForce RTX 5000 series) GPUs, the NVIDIA driver does not enable Resizable BAR automatically, even if it is enabled in firmware. In addition to enabling Above 4G Decoding and Resizable BAR in UEFI, the driver must be explicitly instructed to use it: /etc/modprobe.d/nvidia-rebar.conf options nvidia NVreg_EnableResizableBar=1 Then regenerate the initramfs so the option is applied when the NVIDIA kernel module is loaded early during boot. A full power cycle (shutdown and power off) may be required for PCIe BAR resizing to take effect. Resizable BAR can be verified using lspci -vv, where the GPU BAR size should be larger than 256 MB (example shown is a NVIDIA model 4070Ti Super with 16GB of RAM): # lspci -vv -d ::03xx | grep BAR Capabilities: [bb0 v1] Physical Resizable BAR BAR 0: current size: 16MB, supported: 16MB BAR 1: current size: 16GB, supported: 64MB 128MB 256MB 512MB 1GB 2GB 4GB 8GB 16GB BAR 3: current size: 32MB, supported: 32MB